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- Experimental analysis of the thermal entrainment factor of air curtains in vertical open display cabinets for different ambient air conditionsPublication . Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, R. A.The vertical open refrigerated display cabinets suffer alterations of their thermal performance and energy efficiency due to variations of ambient air conditions. The air curtain provides an aerothermodynamics insulation effect that can be evaluated by the thermal entrainment factor calculation as an engineering approximation or by the calculus of all sensible and latent thermal loads. This study presents the variation of heat transfer rate and thermal entrainment factor obtained through experimental tests carried out for different ambient air conditions, varying air temperature, relative humidity, velocity and its direction relatively to the display cabinet frontal opening. The thermal entrainment factor are analysed and compared with the total sensible and latent heats results for the experimental tests. From an engineering point of view, it is concluded that thermal entrainment factor cannot be used indiscriminately, although its use is suitable to design better cabinet under the same climate class condition.
- Internet of Things Architectures, Technologies, Applications, Challenges, and Future Directions for Enhanced Living Environments and Healthcare Systems: A ReviewPublication . Marques, Gonçalo; Pitarma, R.; Garcia, Nuno M.; Pombo, NunoInternet of Things (IoT) is an evolution of the Internet and has been gaining increased attention from researchers in both academic and industrial environments. Successive technological enhancements make the development of intelligent systems with a high capacity for communication and data collection possible, providing several opportunities for numerous IoT applications, particularly healthcare systems. Despite all the advantages, there are still several open issues that represent the main challenges for IoT, e.g., accessibility, portability, interoperability, information security, and privacy. IoT provides important characteristics to healthcare systems, such as availability, mobility, and scalability, that o er an architectural basis for numerous high technological healthcare applications, such as real-time patient monitoring, environmental and indoor quality monitoring, and ubiquitous and pervasive information access that benefits health professionals and patients. The constant scientific innovations make it possible to develop IoT devices through countless services for sensing, data fusing, and logging capabilities that lead to several advancements for enhanced living environments (ELEs). This paper reviews the current state of the art on IoT architectures for ELEs and healthcare systems, with a focus on the technologies, applications, challenges, opportunities, open-source platforms, and operating systems. Furthermore, this document synthesizes the existing body of knowledge and identifies common threads and gaps that open up new significant and challenging future research directions.
- Detailed CFD modelling of open refrigerated display cabinetsPublication . Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, R. A.A comprehensive and detailed computational fluid dynamics (CFDs) modelling of air flow and heat transfer in an open refrigerated display cabinet (ORDC) is performed in this study. The physical-mathematical model considers the flow through the internal ducts, across fans and evaporator, and includes the thermal response of food products. The air humidity effect and thermal radiation heat transfer between surfaces are taken into account. Experimental tests were performed to characterize the phenomena near physical extremities and to validate the numerical predictions of air temperature, relative humidity, and velocity. Numerical and experimental results comparison reveals the predictive capabilities of the computational model for the optimized conception and development of this type of equipments. Numerical predictions are used to propose geometrical and functional parametric studies that improve thermal performance of the ORDC and consequently food safety.
- CFD parametric studies for global performance improvement of open refrigerated display cabinetsPublication . Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, R. A.A detailed CFD modelling of an open refrigerated display cabinet has been formulated in a previous study. Some modifications are introduced in order to perform parametric studies dealing with low-cost geometrical and functional characteristics for improvement of the global performance and energy efficiency. The parametric studies are devoted to the analysis of the thermal response and behaviour inside the food conservation space influenced by (1) air flow rate through the evaporator heat exchanger; (2) air curtain behaviour; (3) hole dimensions and distribution of the back panel; (4) discharge and return grilles angles; and (5) flow deflectors inside the internal duct. The analysis of the numerical predictions from the parametric studies allows the development of an optimized model for the conception of an open refrigerated display cabinet with a more adequate configuration. The numerical predictions of the optimized model show lower product temperature and reduced electrical energy consumption, allowing the improvement of the food safety and the energy rationalization of the refrigeration equipment.
- Equipamentos Expositores Refrigerados Perspetiva Comercial e EnergéticaPublication . Gaspar, Pedro Dinis; Miranda, Alexandre; Pitarma, Rui A.Com este artigo pretende-se definir os diversos tipos de equipamentos de frio, de conservação e exposição e apresentar na generalidade as características técnicas que os diferenciam. Um dos tópicos do trabalho visa o esclarecimento de diversas particularidades dos equipamentos expositores refrigerados, de modo que durante a selecção dos referidos equipamentos não seja apenas considerado o design e a apresentação final dos produtos, mas também o seu consumo energético.
- Análise experimental da estabilidade de cortinas de ar de equipamentos de refrigeração para diferentes condições do ar ambientePublication . Gaspar, Pedro Dinis; Gonçalves, Luís Carlos Carrilho; Pitarma, Rui A.Os equipamentos de refrigeração abertos ao ar ambiente apresentam alterações do seu desempenho térmico e da eficiência energética devido a variações da temperatura, humidade e velocidade do ar ambiente externo. Estes equipamentos utilizam cortinas de ar para promover a separação térmica e mássica entre os dois espaços contíguos com comportamentos diferenciados ar, a zona de conservação de alimentos e ar ambiente externo. Neste estudo é analisada a estabilidade da cortina de ar presente num equipamento de teste, pela análise de resultados experimentais para diferentes condições do ar ambiente, fazendo uso de vários parãmetros adimensionais: módulo de deflecção e correlação do parâmetro de deflecção obtidos por outros autores em estudos sobre a mesma temática, assim como o cálculo da carga térmica de arrefecimento específica e dos números de Reynolds e de Richardson. Os resultados são comparados com os obtidos nesses estudos, sendo também discutida a velocidade de insuflação que garante a adequada barreira aerotermodinâmica à estabilidade da cortina de ar.