Air-cooled heat exchanger design using successive quadratic programming (SQP)

A nonlinear optimization algorithm is applied to the design of air-cooled heat exchangers. In such equipment, the cold fluid (air) is impelled across banks of finned tubes by means of fans in forced or induced draft. The hot stream flows inside the tubes in one or more passes, and the process that takes place may be cooling of either a gas or a liquid, or condensation of either a pure vapor or a mixture. The objective function is the minimum cost of the unit (investment and operation), subject to certain geometric and thermohydraulic constraints. The optimization algorithm used is that developed by Biegler and Cuthrell [1], and programmed by them in the OPT package. The problem posed in this case is made of 10 optimization variables, subject to five constraints related to geometric and operational parameters of the heat exchanger.Fil: Gonzalez, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Petracci, Noemi Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Urbicain, Martin Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Retention of aroma compounds in basil dried with low pressure superheated steam

Basil leaves were dried using either conventional hot air (50, 60 and 70 °C) and low pressure superheated steam (LPSS) dryers. The effect of the drying method on the retention of some volatile compounds was evaluated. The extraction from the fresh and dried products was performed by the simultaneous distillation-extraction technique. Identification and quantification was performed by capillary gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC) respectively. The identified compounds were 23, with 61% of monoterpenes, 26% of aromatic and 13% of aliphatic compounds, out of which those characteristic of this spice were detected (1,8-cineole, methyl chavicol, methyl cinnamate and linalool). Results show that in the LPSS dried product, the original aroma profile of the fresh vegetable is kept almost constant, while air-dried product shows a significant variation in the relative proportions of aroma compounds. The conclusion is that the LPSS drying technique renders a better product in terms of the aroma compounds content, than the conventional air-drying, with the advantage of being cheaper.Fil: Barbieri, S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Elustondo, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Urbicain, Martin Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Determination and correlation of heat transfer coeffcieints in a falling film evaporator

The aim of the work was to determine the heat transfer parameters of a single effect evaporator under different operating conditions, in order to extrapolate them to a multiple effect unit. The falling film evaporator consisted of 12 stainless steel vertical tubes, 1″ OD and 3 m long, having an evaporation capacity of 240 kg/h. In this unit the conditions of each effect of a multiple effect evaporator were simulated, varying the feed concentration and the pressure, setting in this way the saturation temperature and the transfer regime. Obtained values were correlated by means of an equation that links the heat transfer coefficient with the fluid properties, geometric parameters and flow conditions. Comparison with existing correlations was carried outFil: Prost, J.S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Gonzalez, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Urbicain, Martin Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Optimizing apple juice extraction in multiple presses

A method was developed to find the optimum hydration flow sheet that maximizes either the profit or the soluble solids recovery for a given number of presses in an apple concentrate juice plant. The pomace arising from a press can be wetted with either pure water or dilute juice from downstream presses, or a mixture of both in any proportion. The mass balance around the presses involving any hydration arrangement was posed as an array named connectivity matrix. The connectivity matrix and the economical balance were written in computer code in order to carry out the optimization procedure. The optimization started from a minimum amount of water, and stepwise increasing levels of hydration were evaluated. The best value of this combinatorial search was retained. The optimum arrangement was pure countercurrent in most of cases considered.Fil: Gonzalez, Maria Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Elustondo, M. P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Urbicain, Martin Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Modelado matemático de un desolventizador flash de harinas oleaginosas

Se ha desarrollado un modelo matemático para simular la operaación de un desolventizador flash con vapor sobrecalentado de hexano. El modelo está constituido por un conjunto de ecuaciones diferenciales, que representan los balances de materia,energía y cantidad de movimiento en el sólido y en el vapor y correlaciones para el cálculo de las propiedades de ambas fases y de los coeficientes de arrastre, de fricción y de transferencia de calor. El sistema de ecuaciones diferenciales resultante fue resuelto numéricamente utilizando el software Simulink de Matlab. Las predicciones del modelo se utilizaron para ilustrarlos perfiles de temperatura y velocidad de ambas fases, el con-tenido de hexano residual en la harina y la caída de presión en el equipo. Se analizó el efecto de las principales variables operativas y características del sólido sobre el grado de desolventización, las temperaturas finales y el tiempo de residencia.Fil: Faner, Sandro Ari. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Urbicain, Martin Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Crapiste, Guillermo Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Navigating relapsed hepatoblastoma: Predictive factors and surgical treatment strategy

Abstract Objective Hepatoblastoma (HB) is the most common primary hepatic malignancy in childhood. Relapse occurs in more than 50% of high‐risk patients with a high mortality due to ineffective salvage therapies. The purpose of this study is to identify risk factors for relapsed HB and predictors of survival in a single tertiary referral center. Methods A retrospective chart review showed 129 surgically treated HB patients from October 2004 to July 2020. Of the cohort, 22 patients presented with relapsed HB. Relapse was defined as re‐appearance of malignancy after 4 weeks of normalized AFP and disappearance of all tumors on imaging. Results Patients with relapsed HB had a 5‐year overall survival (OS) of 45.4% compared to 93.1% in those without relapse (p = 0.001). When comparing PRETEXT IV, microvascular invasion, metastatic disease, and age on multivariate logistic regression, only PRETEXT IV was an independent risk factor for relapsed HB with an OR of 2.39 (95% CI: 1.16–4.96; p = 0.019). Mixed epithelial and mesenchymal HB (12/19, 63.2%) was the most common histology of primary tumors while pure epithelial HB (13/15, 86.6%) was the most common relapsed histology. Combination of surgical and medical therapy for relapsed disease was predictive of survival with an HR of 16.3 (95% CI: 1.783–149.091; p = 0.013) compared to only chemotherapy. Conclusions This study demonstrates that PRETEXT IV staging is an independent predictor of relapsed disease. The most common relapsed histology was epithelial, suggesting a potential selection or resistance of this component. Surgical resection is a critical component of multimodal therapy for relapsed HB

Hepatoblastomas with carcinoma features represent a biological spectrum of aggressive neoplasms in children and young adults

Background & aimsHepatoblastoma (HB) and hepatocellular carcinoma (HCC) are the predominant liver cancers in children, though their respective treatment options and associated outcomes differ dramatically. Risk stratification using a combination of clinical, histological, and molecular parameters can improve treatment selection, but it is particularly challenging for tumors with mixed histological features, including those in the recently created hepatocellular neoplasm not otherwise specified (HCN NOS) provisional category. We aimed to perform the first molecular characterization of clinically annotated cases of HCN NOS.MethodsWe tested whether these histological features are associated with genetic alterations, cancer gene dysregulation, and outcomes. Namely, we compared the molecular features of HCN NOS, including copy number alterations, mutations, and gene expression profiles, with those in other pediatric hepatocellular neoplasms, including HBs and HCCs, as well as HBs demonstrating focal atypia or pleomorphism (HB FPAs), and HBs diagnosed in older children (>8).ResultsMolecular profiles of HCN NOS and HB FPAs revealed common underlying biological features that were previously observed in HCCs. Consequently, we designated these tumor types collectively as HBs with HCC features (HBCs). These tumors were associated with high mutation rates (∼3 somatic mutations/Mb) and were enriched with mutations and alterations in key cancer genes and pathways. In addition, recurrent large-scale chromosomal gains, including gains of chromosomal arms 2q (80%), 6p (70%), and 20p (70%), were observed. Overall, HBCs were associated with poor clinical outcomes.ConclusionsOur study indicates that histological features seen in HBCs are associated with combined molecular features of HB and HCC, that HBCs are associated with poor outcomes irrespective of patient age, and that transplanted patients are more likely to have good outcomes than those treated with chemotherapy and surgery alone. These findings highlight the importance of molecular testing and early therapeutic intervention for aggressive childhood hepatocellular neoplasms.Lay summaryWe molecularly characterized a class of histologically aggressive childhood liver cancers and showed that these tumors are clinically aggressive and that their observed histological features are associated with underlying recurrent molecular features. We proposed a diagnostic algorithm to identify these cancers using a combination of histological and molecular features, and our analysis suggested that these cancers may benefit from specialized treatment strategies that may differ from treatment guidelines for other childhood liver cancers