Browsing by Author "Pinto, Pedro Miguel Moreira"
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- Collision Dynamics of a Single Droplet onto a Heated Dry Surface: Jet Fuel and HVO MixturesPublication . Pinto, Pedro Miguel Moreira; Vasconcelos, Daniel; Ribeiro, Daniela; Barata, Jorge M M; Silva, AndréUnderstanding the phenomena behind droplet impact is essential to improve the effectivenessin many industrial applications, such as fuel injection in an internal combustion engine andrapid spray cooling of hot surfaces. This study focuses on an experimental investigation ondroplet impact onto a heated wall. The purpose of this work is to analyse the influence of walltemperature on the morphology of a single droplet impact and observe the possible outcomes.In these experiments, the observation of all heat regimes was possible. Since there is an urgeto implement biofuels in general aviation, the fluids analysed are fuel based. The fluids usedwere distilled water, as a control group, 100% jet fuel, and a mixture of 50% biofuel with 50%jet fuel. This mixture corresponds to the maximum of renewable energy source fuel due to theminimum of 50% of jet fuel required by civil aviation. The impact energy was kept constant, andthe Weber number was set to 320. Furthermore, different wall temperatures were chosen (25◦C−320◦C) to seek every possible impact phenomenon and characterise the impact morphology.The impact dynamics were captured using a high-speed digital camera and the images weredigitally processed.
- Collision Dynamics of a Single Droplet onto a Heated Dry Surface: Jet Fuel and HVO MixturesPublication . Pinto, Pedro Miguel Moreira; Silva, André Resende Rodrigues daThe concern with the environment led the human being to develop new alternative fuels to reduce pollution and mitigate the emission of greenhouse gases. The air transport sector and the burning of fossil fuels are responsible for a huge portion of the pollution. Therefore, introducing new sustainable ways to provide energy, such as biofuel, is of major importance. However, in order to make these new energy sources more efficient and safer, it is necessary to carry out studies related to the injection of fuel into the combustion chambers, and the impact of droplets. This study focuses on an experimental investigation of a single droplet impact onto a heated solid surface. The main purpose of this work is to analyse the influence of wall temperature on the impact morphology of a single droplet and observe the possible outcomes. To do so, in these experimental tests, Jet Fuel and HVO (Hydroprocessed Vegetable Oil) mixtures were used. The fluids tested were: water (as a control group), 100% Jet A-1, 75% Jet A-1 and 25% NExBTL, 50% Jet A-1 and 50% NExBTL, and 100% NExBTL. The present work studies the impact outcomes depending on the working fluids and the wall temperature. The impact energy was kept constant. Therefore, the Weber number in this experiment was set to W e = 320 by varying the droplet diameter or the impact velocity. Furthermore, different wall temperatures were chosen, that vary from Tw = 25ºC to Tw = 330ºC, to seek for every possible impact phenomenon and characterise the impact morphology. The impact dynamics were captured using a high-speed digital camera and the images were digitally processed. It was possible to observe the heat regimes for all fluids, as well as two additional regimes for the mixtures of 75% jet fuel - 25% HVO and 50% jet fuel - 50% HVO.
- Simplified Approach to Predict Food Safety through the Maximum Specific Bacterial Growth Rate as Function of Extrinsic and Intrinsic ParametersPublication . Gaspar, Pedro Dinis; Alves, Joel; Pinto, Pedro Miguel MoreiraCurrently, we assist the emergence of sensors and low-cost information and communication technologies applied to food products, in order to improve food safety and quality along the food chain. Thus, it is relevant to implement predictive mathematical modeling tools in order to predict changes in the food quality and allow decision-making for expiration dates. To perform that, the Baranyi and Roberts model and the online tool Combined Database for Predictive Microbiology (Combase) were used to determine the factors that define the growth of different bacteria. These factors applied to the equation that determines the maximum specific growth rate establish a relation between the bacterial growth and the intrinsic and extrinsic factors that define the bacteria environment. These models may be programmed in low-cost wireless biochemical sensor devices applied to packaging and food supply chains to promote food safety and quality through real time traceability.