Cid Marcos Gonçalves Andrade

Modelagem matemática e análise da hidratação de grãos de ervilha

A mathematical model for estimating the water concentration in pea grains during hydration was developed from a transient water mass balance inside a grain of pea considering a constant volume and spherical geometry. This model is represented by an ordinary first order differential equation and has two parameters: the mass transfer coefficient (Ks) and the equilibrium concentration (ρAeq). Both parameters have been numerically fitted using the minimization of the sum-of-squared residuals criterion and the hydration experimental data for pea grains at 20, 30, 40, 50, and 60 oC. At all temperatures, the model represented the major trends of the hydration process with standard deviations smaller than 5%. For the model fitted parameters, it was observed that the mass transfer coefficient behaved according to Arrheniuss equation in relation to the temperature variation, Ks = 182.8.exp(-3521/T) while the equilibrium concentration remained practically constant showing an average value of ρAeq = 0.533 g/cm3. Using the Ks Arrheniuss correlation and assuming the average value of ρAeq, a generalized model was obtained, which resulted in a standard deviation slightly greater than 7% for all the data values. Additionally, it was observed that the pea grains density remains practically constant along the hydration process and does not depend on the temperature.

Novo modelo de parâmetros concentrados aplicado à hidratação de grãos

A new first principle model with lumped parameters was developed for the hydration of soya beans. A transient mass balance was applied to the soya beans taking into consideration two basic hypotheses:1o) variation of the volume directly proportional to the variation of the mass of the grain during the process, 2o) Exponential variation of the apparent coefficient of mass transfer in function of water concentration in the soy. This model has got just two parameters, which were evaluated from adjustment of model to the measures of grain moisture along the time, at several temperatures. The results indicate that the proposed model was able to represent the hydration process, while the mass transfer coefficient depends on the temperature and it presents significant variations along the hydration.

Modelagem e validação da hidratação de grãos de soja

SUMMARY MODELING AND VALIDATION OF SOYA BEAN HYDRATION. A first principle model with lumped parameters was developed for the hydration of soya beans. A transient mass balance was applied to the soya beans taking into consideration the variation of the bean diameters during the process. Simulation results were compared to the empirical models available in the literature and with experimental data. Both the first principle and empirical models were validated by the experimental data that were obtained for the temperatures of 10, 15, 20, 30, 42 and 49°C. All models were able to represent the main data trends of the hydration process, after adjustment of their parameters for each temperature. However, the first principle model has the smallest deviations in relation to the experimental data. In addition, a generalized first principle model was proposed.

Application of the Hsu model to soybean grain hydration

Abstract A comparative analysis of the theoretical-experimental study, developed by Hsu on the hydration of Amsoy 71 soybean grain, was performed through several soaking experiments using CD 202 soybean at 10, 20, 30, 40, and 50 °C, measuring moisture content over time. The results showed that CD 202 soybean equilibrium moisture content, X eq , does not depend on temperature and is 21% higher than that found by Hsu, suggesting that soybean cultivar exerts great influence on X eq . The Hsu model was numerically solved and its parameters were adjusted by the least squares method, with maximum deviations of +/– 10% relative to the experimental values. The limiting step in the mass transfer process during hydration corresponds to water diffusion inside the grain, leading to radial moisture gradients that decrease over time and with an increase in temperature. Regardless of the soybean cultivar, diffusivity increases as temperature or moisture content increases. However, the values of this transport property for Amsoy 71 were superior to those of CD 202, very close at the beginning of hydration at 20 °C and almost three times higher at the end of hydration at 50 °C.

Modeling of the soybean grains hydration by a distributed parameters approach.

A mathematical model with distributed parameters was proposed to describe the absorption of water by soybeans, in order to evaluate the moisture content variation with time inside the grains. This model was represented by a partial differential equation (second order relative to position and first order relative to time), whose parameters were numerically adjusted using a minimum squares method. For this purpose, available MATLAB® routines were used, together with experimental data obtained from hydration tests where soybeans were immersed in liquid water at temperatures of 10, 20, 30, 42 and 49°C. According to the results, the model was able to represent the main characteristics of the hydration process, with a maximum deviation of 10% in the whole set of experimental conditions.

Inertial Environment Small Alloy Welding Equipment

Welding is the most common process to join two types of metal. Capacitive welding is used in small alloys, jewelry and temperature sensors. A good quality welding is composed by a homogeneous distribution and uniformity of the material at welding point and a mass conservation, keeping the metal crystalline proprieties. Capacitive welding consists in submitting a metal to an electric arc, storing energy in capacitors, when released will melt alloy and creates a union. In an inertial chamber the atmosphere is controlled, and Argon is injected by a solenoid valve, responsible to control Argon from a cylinder. Argon is a shielding gas responsible for the non-inclusion of external elements in the weld. This study develops equipment able to make capacitive welding using the principles mass and energy conservation in alloys and gauges pre-established, of different types of metals in an inertial environment, with the objective of create a good quality and efficient weld with low cost equipment with easy manipulation.

Computer-aided visual inspection

The quality control in industrial processes and production lines is increasingly rigorous due to governmental issues and the competition among other industries. These make new studies in this field even more important, especially on defects analysis and visual inspection. Among the methods of inspections commonly used the highlighted ones include the direct inspection that is performed without the aid of optical devices, and the remote inspection that makes use of optical instruments, both having an inspector responsible for a subjective evaluation. Such methods are usually the first used in quality control of products. In this paper we propose a remote and automatic computational image analysis to verify the presence of defects in products in a production line.

Reviewing case study 12S.2 product and process design principles: Synthesis, analysis and evaluation book

The industries often require heat exchanger network (HEN) that supports variations in the streams thermal capacity and temperatures. Therefore, the HEN project must consider the concepts of flexibility, controllability and resiliency. This paper presents a review of the case study 12S.2 proposed by Seider et al. (2009)for analysis of operability using the RGA and DC index. The results found are the diagonal coupling of controlled and manipulatedvariables and the desirable resilience, obtaining economically improved solution than the proposed by the authors.

Themodynamic controlabillity assessment focused on heat exchanger networks

In recent times, the interaction between process design and control has become the focus of research and development, because not always the best process design features the best dynamic performance, with implications in the controllability of the plant. It is then proposed a simultaneous approach of economic goals and controllability in the early stages of the project design. Recent studies have shown that a thermodynamic analysis with a dissipative approach, can lead to reaching how much a process can be integrated while not compromising its controllability. In this paper we use a methodology proposed by Meeuse et al (2004) where we can obtain a response time, as a measure of controllability of our process system applied to a heat exchanger network, showing the relation between energy and entropy production and process controllability.