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Computational tool to evaluate the efficency of hydrogen in internal combustion engines
(Universidade Federal de Lavras, 2025-03-20) Rincon, Alvaro Ferney Algarra; Alvarez, Carlos Eduardo Castilla; Ensinas, Adriano Viana; Rodriguez, Christian Jeremi Coronado
Behavioral studies on the efficiency of a hydrogen engine are important, as they are part of a global initiative to decarbonize the automotive sector, and this technological route for the use of hydrogen is promising within recent energy transition studies. In this sense, the exploration of new technological development routes around production, commercialization and use of hydrogen for the state of Minas Gerais and for Brazil has been proposed through various government initiatives in recent years. For this reason, this work has developed a computational tool based on a zero-dimensional mathematical model capable of predicting the efficiency of a spark ignition engine when using hydrogen as fuel. The simplicity of the model offers a quick view of the operation and thermodynamics of the engine, which reduces computational effort and produces results that represent the real behavior of hydrogen combustion. This focus helps in the study of combustion and in making decisions about the economic viability of using hydrogen in internal combustion engines. To do this, the compression, combustion and expansion processes in the Otto cycle were mathematically modeled to represent the combustion behavior of the air-hydrogen blend inside the engine cylinder, using code written in MATLAB. The mathematical model was validated with experimental data taken from the research engine bench and those reported in the literature in relation to the pressure curve for the different engines and operating conditions evaluated, and the efficiency produced by the engine under these conditions was estimated. A graphical interface was generated in AppDesigner for the computational tool, making it easier for the user to develop the behavioral and operational study of a hydrogen engine. The results obtained with the computational tool show that the estimated pressure and efficiency values are in good agreement with those found in the literature in all the cases evaluated. The maximum error when comparing the pressure curve was 1.32% for an engine with a speed of 3300 RPM. In addition, the minimum fit of the mathematical model to the experimental data was 86%, which represents a good alternative for estimating the thermal efficiency value.
Castanhas-do-brasil produzidas ex-situ : caracterização física, sensorial e estabilidade durante o armazenamento
(Universidade Federal de Lavras, 2026-03-27) Passos, Louise Paiva; Pinheiro, Ana Carla Marques; Nunes, Cleiton Antônio; Melo, Lucas Amaral de; Guimarães, Jéssica Sousa; Ribeiro, Michele Nayara
The Brazil nut tree (Bertholletia excelsa) is widely recognized for its kernels of high commercial value due to their composition rich in unsaturated fatty acids and minerals. However, most studies on its cultivation have focused on its native region, with few experiments conducted outside this context. Recently, fruiting of the species was observed in an experiment carried out in Lavras, Minas Gerais, Brazil, suggesting the possibility of expanding its production beyond its natural area of occurrence. The objective of this study was to evaluate the characteristics of kernels produced ex-situ in Lavras, Minas Gerais, using nuts from the native region as a comparative reference. The evaluations included analyses of physical dimensions, density, color, and sensory characterization, as well as color analysis, specific extinction, and sensory analysis to assess the stability over time of nuts stored with shell and without shell. The results showed no differences between nuts from the Northern region and those from UFLA for most of the physical parameters analyzed. Specific differences were identified, such as higher density values for kernels from UFLA. In the sensory characterization, distinctions related to shell size and coloration were observed, while similarities were found in flavor attributes; kernels from both origins were described as having a mild, pleasant, and slightly sweet taste. During storage, nuts maintained with the shell showed greater sensory and instrumental stability over time. It can be concluded that the nuts produced ex-situ in Lavras, Minas Gerais, present physical and sensory characteristics comparable to those observed in nuts originating from the species’ natural region of occurrence. The differences observed among samples are subtle and fall within the variability already described for Brazil nuts, possibly influenced by edaphoclimatic factors and cultivation conditions, demonstrating the feasibility of producing the species outside its native range.
La amenaza velada al acceso abierto diamante: cuando los indicadores se convierten en armas de exclusión
(UFLA, 2025-07-27) Ribeiro, Nivaldo Calixto
Teste
Valorização de tilápia: obtenção de concentrado protéico e aplicação na produção de filmes
(Universidade Federal de Lavras, 2026-03-27) Miranda, Ana Luiza de Souza; Ramos, Alcinéia de Lemos Souza; Oliveira, Diana Carla Fernandes; Paula, Marielle Maria de Oliveira; Souza, André Luiz Medeiros de; Melo, Nathalia Ramos de
The growth of aquaculture and fish consumption has been accompanied by an increase in the generation of by-products from industrial processing. These by-products, which include carcasses, trimmings, and unused fish fractions, as well as underutilized whole fish that do not meet commercial weight and size standards, represent an important source of biomolecules with high nutritional value, especially proteins. In this context, strategies for adding value to these materials have aroused interest, contributing to the full utilization of resources in the production chain and to the reduction of environmental impacts. Therefore, this study aimed to evaluate the potential of processing by-products and underutilized whole tilapia (Oreochromis niloticus) fish, as well as different extraction solutions (aqueous and saline), for obtaining proteins. The following were used as raw materials: mechanically separated meat (MSM) obtained from carcasses (C), a mixture of carcass and trimmings in a “V” shape (CV), as well as whole fish with skin and head (C/P) and whole fish without skin and head (S/P), all previously eviscerated. The raw materials were processed to obtain surimi through three successive washing cycles, followed by the addition of cryoprotectants (sucrose and polyphosphate). The four surimis obtained were characterized in terms of centesimal composition, pH, water activity, collagen, yield, and color. Subsequently, the proteins were recovered by solubilization at different pH values, in aqueous and saline media, followed by isoelectric precipitation, and protein solubility curves were determined. The precipitated proteins were characterized in terms of moisture, protein content, yield, and color. The recovered proteins were applied in the development of biodegradable films and in the production of powdered protein concentrates. The films were evaluated for their physical, mechanical, optical, structural, permeability, and biodegradability properties, while the protein powders were characterized in terms of chemical composition, yield, technological, techno-functional, and nutritional properties. The results demonstrated that the nature of the raw material influenced the characteristics of the surimi. The solubility curves showed typical behavior of muscle proteins as a function of pH and allowed the definition of the appropriate range for protein precipitation and recovery. In the biodegradable films, the origin of the raw material influenced the material's performance, with greater mechanical resistance observed in the C/P films, possibly associated with a higher collagen content, as well as affinity for water and rapid biodegradation in aqueous medium. For the protein concentrate powders, the extraction medium and raw materials influenced the characteristics of the recovered proteins, with higher yield and protein content observed in the extraction in aqueous solution. The concentrates showed the presence of essential amino acids, relevant technofunctional properties, and structural and color differences related to the extraction medium. Overall, the results demonstrate that tilapia by-products and underutilized fish are promising raw materials for protein recovery and valorization, contributing to the development of sustainable food ingredients and biomaterials, as well as reducing environmental impacts in the aquaculture chain.