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- PublicaciónAcceso abiertoEvaluating the performance of a cellular manufacturing system proposal for the sewing department of a sportswear manufacturing company: A simulation approach(2022-03-02)Cellular manufacturing systems (CMS) are a major application of group technology, that brings benefits related to the reduction of wastes, also known as ‘mudas’ in lean manufacturing philosophy, to organisations striving to compete on today’s markets. These benefits include the reduction of machine setup times, material handling and work-in-process inventory, among others. However, many organisations are reluctant to implement such decisions in their production systems, due to the uncertainty and economic and productive impact that these involve. For this reason, a simulation study is performed in this paper to evaluate the performance of a cellular manufacturing system approach for the sewing department of a sportswear manufacturing company. The simulation study was designed, and the results of the proposed model showed improvements of 51,46% in the average flow time, 1102,52% in the average throughput, and 50,65% in the average setup times of machines, compared to the current state of the case study.
- PublicaciónAcceso abiertoThermodynamics performance optimization of a hybrid solar gas turbine power plant in Colombia(2022-01-05). A thermodynamic model is presented for evaluation of a solar hybrid gas-turbine power plant. The model uses variable ambient temperature and estimates direct solar radiation at different day times. The plant is evaluated in Barranquilla, Colombia, with a solar concentration system and a combustion chamber that burns natural gas. The hybrid system enables to maintain almost constant the power output throughout day. The model allows optimizing the different plant parameters and evaluating maximum performance point. This work presents pressure ratio ranges where the maximum values of overall efficiency, power output, thermal engine efficiency and fuel conversion rate are found. The study is based on the environmental conditions of Barranquilla, Colombia. The results obtained shows that optimum pressure ratio range for power output and overall efficiency is between 6.4 and 8.3, when direct solar radiation its maximum at noon. This thermodynamic analysis is necessary to design new generations of solar thermal power plants.
- PublicaciónAcceso abiertoEffect of a regenerator on hybrid solar gas turbine performance in Barranquilla, Colombia(2021)A thermodynamic analysis of a hybrid gas turbine solar plant, represented in three basic subsystems related to the power cycle, the combustion chamber subsystem, and the solar concentrator subsystem, allows evaluating the performance of a hybrid cycle from a reduced number of parameters, which include energy losses in each of its components. The solar radiation values are estimated with an evaluated and validated theoretical model, the combustion chamber uses natural gas as fuel and the numerical values of the system are taken from the Solugas experimental plant in Spain. This work presents an integrated model that allows to estimate the operation of a hybrid solar Brayton power plant in any place and day of the year. The evaluation of the plant in Barranquilla, Colombia is shown from the influence of the regenerator has on the plant performance and solar concentrating system. The results show that the regenerator can increase the overall efficiency of the plant by 29% and allows reaching a maximum temperature of the central receiver of the concentrator of 1044 K at noon, when solar radiation is maximum.
- PublicaciónAcceso abiertoHydrogen production from palm kernel shell(ELSEVIER, 2019-11-19)The hydrogen production process from palm kernel shell (PKS) is modeled and simulated by a steady-state gasification system using Aspen PLUS®. The kinetic parameters of the gasification are determined by employing thermogravimetric analysis (TG/DTG) using two gasifying agents (CO2 and steam) and applying three semi-empirical kinetic models to interpret the experimental results (linear model, grain model, and volumetric model). The process was subjected to different temperatures (750–950 °C) and different compositions of the steam/biomass ratio (S/B) (0–2.5). It is obtained that the linear model and the grain model have the best R2 with the gasification results of the PKS with steam (0.966) and CO2 (0.965), respectively. The steam reaction kinetic parameters obtained were and and for the reaction with CO2, they were and. The production yield of H2 (109 g H2/PKS kg) is reached at the highest temperature (950 °C) and the lowest S/B ratio (0). It is concluded that the model can predict with greater precision the hydrogen composition in the syngas, with a 0.135 mean square error, compared to other authors that present a 0.282 mean square error.
- PublicaciónAcceso abiertoEnzymatic transesterification ofwaste frying oil from local restaurants in east colombia using a combined lipase system(MDPI, 2020-05-21)The search for innovation and biotechnological strategies in the biodiesel production chain have become a topic of interest for scientific community owing the importance of renewable energy sources. This work aimed to implement an enzymatic transesterification process to obtain biodiesel from waste frying oil (WFO). The transesterification was performed by varying reaction times (8 h, 12 h and 16 h), enzyme concentrations of lipase XX 25 split (14%, 16% and 18%), pH of reaction media (6, 7 and 8) and reaction temperature (35, 38 and 40 °C) with a fixed alcohol–oil molar ratio of 3:1. The optimum operating conditions were selected to quantify the amount of fatty acid methyl esters (FAMEs) generated. The highest biodiesel production was reached with an enzyme concentration of 14%, reaction time of 8 h, pH of 7 and temperature of 38 °C. It was estimated a FAMEs production of 42.86% for the selected experiment; however, best physicochemical characteristics of biodiesel were achieved with an enzyme concentration of 16% and reaction time of 8 h. Results suggested that enzymatic transesterification process was favorable because the amount of methyl esters obtained was similar to the content of fatty acids in the WFO.