Current research focus is drying of particulate materials in continuous flow driers, especially vibrating fluidised bed driers Supervisors: Emeritus Professor Joaquin Martinez Phone: +46 8 790 6570 (Work) Address: Dept of Chemical Engineering and Technology
Royal Institute of Technology (KTH)
Teknikringen 42 plan 4
SE-114 28 Stockholm
Sweden
In this study, drying kinetics and thermodynamic analysis of tomato were conducted in a tunnel dr... more In this study, drying kinetics and thermodynamic analysis of tomato were conducted in a tunnel dryer. Drying experiments were performed at three temperatures (100, 115, and 130 °C) and an air velocity of 1.45 m/s. From the drying curves, only a falling rate period was observed. Under these conditions, a characteristic drying curve was determined. It is observed that at the 40 minutes of the drying process, the outlet gas enthalpy achieved a maximum value that is very close to the inlet value and remained constant until the end of the process. Entropy exhibited similar behaviour to enthalpy. The maximum value of the exergy efficiency curve corresponds to the maximum value observed within the drying rate curves. This maximum value represents the stage when the available energy is efficiently used in moisture removal. As the drying rate decreases the available energy is started to be less employed.
The performance of continuous vibrating fluidised bed drying of corn grits was simulated (using a... more The performance of continuous vibrating fluidised bed drying of corn grits was simulated (using a previously validated mathematical model) and analysed based on the first- and second law of thermodynamics. The energy and exergy analyses were performed for several drying conditions. The effects of inlet air velocity and temperature, vibration intensity, and particle size on the efficiencies and inefficiencies of drying process have been simulated and discussed. Generally, application of vibration during fluidised bed drying enhanced the drying process. The application of higher levels of drying air temperature and velocity led in higher exergy efficiencies and energy utilisation. Also, the exergy loss had maximum value when higher drying air temperature and velocity were used for the drying process.
In this study, a mathematical model to simulate the drying of shelled corn in a continuous plug-f... more In this study, a mathematical model to simulate the drying of shelled corn in a continuous plug-flow fluidised bed dryer is presented. Equipment and material models were applied to describe the process. The equipment model was based on the differential equations obtained by applying mass and energy balances to each element of the dryer. In the case of the material model, mass and heat transfer rates in a single isolated particle were considered. Calculation results were verified by comparison with experimental data from the literature. There was a very good agreement between experimental data and simulation. The effects of gas temperature and velocity, particle diameter, dry solid flow and solid temperature on the drying process were investigated. It was found that the changes in gas velocity, dry solids flow and the solid temperature had essentially no effect on the drying process.
Este artículo explora los orígenes de la Ingeniería Química. Se trata principalmente del surgimie... more Este artículo explora los orígenes de la Ingeniería Química. Se trata principalmente del surgimiento del concepto de Ingeniería Química, el reconocimiento del campo como una disciplina independiente y su desarrollo inicial. Si bien la concepción de Ingeniería Química tiene lugar en Gran Bretaña, la disciplina se desarrolló fundamentalmente en los Estados Unidos, donde pronto tomó la forma en que la conocemos hoy. Dos décadas después de la concepción, la nueva disciplina encontró su espacio en universidades latinoamericanas (Chile, Argentina). La disciplina y profesión se desarrolló a medida que la propia industria crecía rápidamente, en respuesta a una demanda creciente de la sociedad por los productos de la industria química. Se consolidó la creación de la Ingeniería Química como programa académico y se ofertó en muchos países, tanto en aquellos con tradición en educación en el área, como en otros en donde el programa fue una novedad.
Vaccines against SARS-CoV-2 have been rapidly developed and deployed globally as a measure to com... more Vaccines against SARS-CoV-2 have been rapidly developed and deployed globally as a measure to combat COVID-19. These vaccines have been demonstrated to confer significant protection, but there have been reports of temporal decay in neutralising antibody titers. In addition, variants of SARS-CoV-2 (e.g., omicron) with varying degrees of resistance to antibodies have been identified. These two factors may suggest that a booster dose is worthy of consideration, especially in immunocompromised persons. As an alternative for enhancing the immune response, a heterologous booster strategy has been proposed to elicit both humoral and cell-mediated immune responses that could lead to robust, broad, and long-lasting immunity. In this review, some results of heterologous booster dose clinical trials against COVID-19 are reported.
Several vaccines against COVID-19 have received Emergency Use Authorisation (EUA), such as Comirn... more Several vaccines against COVID-19 have received Emergency Use Authorisation (EUA), such as Comirnaty™, Vaxzevria™, Spikevax™, CoronaVac<sup>®</sup>, and Covaxin<sup>®</sup>, amongst others. Unfortunately, global access to vaccines is not uniform, and some countries have minimal population access to them. Therefore, different vaccination strategies are being studied including vaccination with heterologous regimens for the second dose, thus facilitating mass vaccination. Further, it is hypothesised that such heterologous regimens may also prove very effective in combating emerging SARS-CoV-2 variants (e.g., delta plus). Currently, several clinical trials are analysing the safety, reactogenicity, and immunogenicity of these heterologous regimens. In this review, some results of clinical trials of heterologous vaccination regimes against COVID-19 are reported.
En el presente estudio se analizó la producción científica de Nicaragua en el Science Citation In... more En el presente estudio se analizó la producción científica de Nicaragua en el Science Citation Index Expanded durante el período 2007-2009. Se recopiló un total de 216 publicaciones distribuidas en 150 revistas. Su análisis global mostró una actividad creciente que alcanzó alrededor del 47 %. La distribución de campos temáticos mostró un aporte mayoritario en la medicina (30 %), seguido por las ciencias agrícolas y biológicas (16 %) y la ciencia ambiental (12 %). La UNAN-León constituyó la institución Nicaragüense más productiva, con un aporte del 25 % al total de publicaciones. El 95 % de las publicaciones se realizaron en colaboración con investigadores provenientes de 62 países.
The thin-layer drying characteristics of instant coffee solution were investigated in a laborator... more The thin-layer drying characteristics of instant coffee solution were investigated in a laboratory tunnel dryer. Drying experiments were carried out at three temperatures (80, 100 and 120 °C) and at an air velocity of 1.2 m/s. Drying experimental data obtained are fitted to six (6) thin-layer drying models using the non-linear least squares regression analysis. The acceptability of the thin-layer drying model has been based on a value of the correlation coefficient that should be close to one, and low values for root mean square error (<em>RMSE</em>) and chi-square (<em>c</em><sup>2</sup>). According to this evaluation, the most suitable model for describing drying process of thin-layer instant coffee solution is the Page model. Further, the effective moisture diffusivity and the activation energy were computed employing the drying experimental data. The effective moisture diffusivity values varied from 1.6133 × 10<sup>-9</sup> to 1.62...
The purpose of this work is to experimentally study the feasibility of improving the processing o... more The purpose of this work is to experimentally study the feasibility of improving the processing of neem flakes in columns by performing the leaching of insecticide without intermediate removal of the non-polar solvent and by performing simultaneously both leaching steps. ...
ABSTRACT A mathematical model for the drying of grain in a continuous vibrating fluidized bed drye... more ABSTRACT A mathematical model for the drying of grain in a continuous vibrating fluidized bed dryer was developed. Simple equipment and material models were applied to describe the process. In the plug-flow equipment model, a thin layer of particles moving forward and well mixed in the direction of the gas flow was examined. Mass and heat transfer within a single wet particle was described by effective transport coefficients. Assuming constant effective mass transport coefficient and thermal conductivity, analytical solutions of the mass and energy balances were obtained. The variation in both transport coefficients along the dryer was taken into account by a stepwise application of the analytical solution in space intervals with averaged coefficients from previous locations in the dryer. Calculation results were in fairly good agreement with experimental data from the literature. However, the results depend strongly on relationships used to determine the heat and mass transfer coefficients; because the results from correlations found in the literature vary considerably, the correlations should be adapted to the specific equipment in order to obtain reliable results.
ABSTRACT A mathematical model for the drying of grain in a continuous vibrated fluidised bed drye... more ABSTRACT A mathematical model for the drying of grain in a continuous vibrated fluidised bed dryer was developed. A plug-flow equipment model in which, a thin layer of particles moving forward and well mixed in the direction of the gas flow was applied. Mass and heat ...
The purpose of this work is to experimentally study the feasibility of improving the processing o... more The purpose of this work is to experimentally study the feasibility of improving the processing of neem flakes in columns by performing the leaching of insecticide without intermediate removal of the non-polar solvent and by performing simultaneously both leaching steps. ...
In this study, a mathematical model to simulate the drying of rough rice in a continuous plug-flo... more In this study, a mathematical model to simulate the drying of rough rice in a continuous plug-flow fluidised bed dryer ispresented. Equipment and material models were applied to describe the process. The equipment model was based on thedifferential equations obtained by applying mass and energy balances to each element of the dryer. Concerning the materialmodel, mass and heat transfer rates in a single isolated particle were considered. Mass and heat transfer within the particles wasdescribed by analytical solutions with constant effective transport coefficients. To simulate the dryer, the material model wasimplemented in the equipment model in order to describe the whole process. Calculation results were verified by comparisonwith experimental data from the literature. There was very good agreement between experimental data and simulation. Theeffects of gas temperature and velocity, particle diameter, dry solid flow and solid temperature on the drying process wereinvestigated. It w...
An experimental study was carried out to determine the effect of strontium (Sr) on the characteri... more An experimental study was carried out to determine the effect of strontium (Sr) on the characteristic of intermetallic phases, particularly the Al5FeSi phase which present morphology of platelets or needle-like. The results showed that within the range of variables studied, the modification process caused the disappearance of the needles and only occur the precipitation of phase α (chinese script-like). Refinement of the intermetallic phases occurs in conjunction with the refinement in grain size. Both parameters depend strongly on local cooling rate (T), temperature gradient (G) and apparent rate of solidification front (V). In the case of equiaxed structures the refinement of grain size and intermetallic occurs with increasing local cooling rate and temperature gradient and decrease the apparent rate of solidification front. In the case of columnar structures, refinement of grains and intermetallic requires the increase in values of the three variables indicated. Moreover, the add...
&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;El objet... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;El objetivo de este trabajo es estudiar experimentalmente la viabilidad de mejorar el procesamiento de hojuelas de nim en columnas, mediante la realización de la lixiviación del insecticida sin la remoción intermedia del solvente no-polar; y mediante la simultánea realización de ambas etapas de lixiviación. El secado de los solventes remanentes en las hojuelas de nim también se estudió experimentalmente. En la parte de lixiviación, los parámetros estudiados fueron tiempo de lixiviación, grosor de hojuelas, relación de volumen de solventes y volumen total de solventes. Estos parámetros mostraron tener una gran influencia en el rendimiento de los compuestos insecticidas, pero la influencia de la relación de solventes fue la más importante. Se demostró que más metanol que hexano tuvo que ser empleado para obtener un mayor rendimiento de compuestos insecticidas. El rendimiento de aceite fue influenciado principalmente por el grosor de las hojuelas. En la parte de secado, la temperatura del flujo de aire entrante tiene influencia en el proceso. Conclusiones sobre el tiempo de secado o la velocidad de secado no son posibles de realizar a partir de los resultados de los experimentos. Las variaciones en el tiempo de secado son demasiadas grandes y la velocidad de secado parece ser independiente de las condiciones de la etapa de lixiviación anterior.&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;
In this study, drying kinetics and thermodynamic analysis of tomato were conducted in a tunnel dr... more In this study, drying kinetics and thermodynamic analysis of tomato were conducted in a tunnel dryer. Drying experiments were performed at three temperatures (100, 115, and 130 °C) and an air velocity of 1.45 m/s. From the drying curves, only a falling rate period was observed. Under these conditions, a characteristic drying curve was determined. It is observed that at the 40 minutes of the drying process, the outlet gas enthalpy achieved a maximum value that is very close to the inlet value and remained constant until the end of the process. Entropy exhibited similar behaviour to enthalpy. The maximum value of the exergy efficiency curve corresponds to the maximum value observed within the drying rate curves. This maximum value represents the stage when the available energy is efficiently used in moisture removal. As the drying rate decreases the available energy is started to be less employed.
The performance of continuous vibrating fluidised bed drying of corn grits was simulated (using a... more The performance of continuous vibrating fluidised bed drying of corn grits was simulated (using a previously validated mathematical model) and analysed based on the first- and second law of thermodynamics. The energy and exergy analyses were performed for several drying conditions. The effects of inlet air velocity and temperature, vibration intensity, and particle size on the efficiencies and inefficiencies of drying process have been simulated and discussed. Generally, application of vibration during fluidised bed drying enhanced the drying process. The application of higher levels of drying air temperature and velocity led in higher exergy efficiencies and energy utilisation. Also, the exergy loss had maximum value when higher drying air temperature and velocity were used for the drying process.
In this study, a mathematical model to simulate the drying of shelled corn in a continuous plug-f... more In this study, a mathematical model to simulate the drying of shelled corn in a continuous plug-flow fluidised bed dryer is presented. Equipment and material models were applied to describe the process. The equipment model was based on the differential equations obtained by applying mass and energy balances to each element of the dryer. In the case of the material model, mass and heat transfer rates in a single isolated particle were considered. Calculation results were verified by comparison with experimental data from the literature. There was a very good agreement between experimental data and simulation. The effects of gas temperature and velocity, particle diameter, dry solid flow and solid temperature on the drying process were investigated. It was found that the changes in gas velocity, dry solids flow and the solid temperature had essentially no effect on the drying process.
Este artículo explora los orígenes de la Ingeniería Química. Se trata principalmente del surgimie... more Este artículo explora los orígenes de la Ingeniería Química. Se trata principalmente del surgimiento del concepto de Ingeniería Química, el reconocimiento del campo como una disciplina independiente y su desarrollo inicial. Si bien la concepción de Ingeniería Química tiene lugar en Gran Bretaña, la disciplina se desarrolló fundamentalmente en los Estados Unidos, donde pronto tomó la forma en que la conocemos hoy. Dos décadas después de la concepción, la nueva disciplina encontró su espacio en universidades latinoamericanas (Chile, Argentina). La disciplina y profesión se desarrolló a medida que la propia industria crecía rápidamente, en respuesta a una demanda creciente de la sociedad por los productos de la industria química. Se consolidó la creación de la Ingeniería Química como programa académico y se ofertó en muchos países, tanto en aquellos con tradición en educación en el área, como en otros en donde el programa fue una novedad.
Vaccines against SARS-CoV-2 have been rapidly developed and deployed globally as a measure to com... more Vaccines against SARS-CoV-2 have been rapidly developed and deployed globally as a measure to combat COVID-19. These vaccines have been demonstrated to confer significant protection, but there have been reports of temporal decay in neutralising antibody titers. In addition, variants of SARS-CoV-2 (e.g., omicron) with varying degrees of resistance to antibodies have been identified. These two factors may suggest that a booster dose is worthy of consideration, especially in immunocompromised persons. As an alternative for enhancing the immune response, a heterologous booster strategy has been proposed to elicit both humoral and cell-mediated immune responses that could lead to robust, broad, and long-lasting immunity. In this review, some results of heterologous booster dose clinical trials against COVID-19 are reported.
Several vaccines against COVID-19 have received Emergency Use Authorisation (EUA), such as Comirn... more Several vaccines against COVID-19 have received Emergency Use Authorisation (EUA), such as Comirnaty™, Vaxzevria™, Spikevax™, CoronaVac<sup>®</sup>, and Covaxin<sup>®</sup>, amongst others. Unfortunately, global access to vaccines is not uniform, and some countries have minimal population access to them. Therefore, different vaccination strategies are being studied including vaccination with heterologous regimens for the second dose, thus facilitating mass vaccination. Further, it is hypothesised that such heterologous regimens may also prove very effective in combating emerging SARS-CoV-2 variants (e.g., delta plus). Currently, several clinical trials are analysing the safety, reactogenicity, and immunogenicity of these heterologous regimens. In this review, some results of clinical trials of heterologous vaccination regimes against COVID-19 are reported.
En el presente estudio se analizó la producción científica de Nicaragua en el Science Citation In... more En el presente estudio se analizó la producción científica de Nicaragua en el Science Citation Index Expanded durante el período 2007-2009. Se recopiló un total de 216 publicaciones distribuidas en 150 revistas. Su análisis global mostró una actividad creciente que alcanzó alrededor del 47 %. La distribución de campos temáticos mostró un aporte mayoritario en la medicina (30 %), seguido por las ciencias agrícolas y biológicas (16 %) y la ciencia ambiental (12 %). La UNAN-León constituyó la institución Nicaragüense más productiva, con un aporte del 25 % al total de publicaciones. El 95 % de las publicaciones se realizaron en colaboración con investigadores provenientes de 62 países.
The thin-layer drying characteristics of instant coffee solution were investigated in a laborator... more The thin-layer drying characteristics of instant coffee solution were investigated in a laboratory tunnel dryer. Drying experiments were carried out at three temperatures (80, 100 and 120 °C) and at an air velocity of 1.2 m/s. Drying experimental data obtained are fitted to six (6) thin-layer drying models using the non-linear least squares regression analysis. The acceptability of the thin-layer drying model has been based on a value of the correlation coefficient that should be close to one, and low values for root mean square error (<em>RMSE</em>) and chi-square (<em>c</em><sup>2</sup>). According to this evaluation, the most suitable model for describing drying process of thin-layer instant coffee solution is the Page model. Further, the effective moisture diffusivity and the activation energy were computed employing the drying experimental data. The effective moisture diffusivity values varied from 1.6133 × 10<sup>-9</sup> to 1.62...
The purpose of this work is to experimentally study the feasibility of improving the processing o... more The purpose of this work is to experimentally study the feasibility of improving the processing of neem flakes in columns by performing the leaching of insecticide without intermediate removal of the non-polar solvent and by performing simultaneously both leaching steps. ...
ABSTRACT A mathematical model for the drying of grain in a continuous vibrating fluidized bed drye... more ABSTRACT A mathematical model for the drying of grain in a continuous vibrating fluidized bed dryer was developed. Simple equipment and material models were applied to describe the process. In the plug-flow equipment model, a thin layer of particles moving forward and well mixed in the direction of the gas flow was examined. Mass and heat transfer within a single wet particle was described by effective transport coefficients. Assuming constant effective mass transport coefficient and thermal conductivity, analytical solutions of the mass and energy balances were obtained. The variation in both transport coefficients along the dryer was taken into account by a stepwise application of the analytical solution in space intervals with averaged coefficients from previous locations in the dryer. Calculation results were in fairly good agreement with experimental data from the literature. However, the results depend strongly on relationships used to determine the heat and mass transfer coefficients; because the results from correlations found in the literature vary considerably, the correlations should be adapted to the specific equipment in order to obtain reliable results.
ABSTRACT A mathematical model for the drying of grain in a continuous vibrated fluidised bed drye... more ABSTRACT A mathematical model for the drying of grain in a continuous vibrated fluidised bed dryer was developed. A plug-flow equipment model in which, a thin layer of particles moving forward and well mixed in the direction of the gas flow was applied. Mass and heat ...
The purpose of this work is to experimentally study the feasibility of improving the processing o... more The purpose of this work is to experimentally study the feasibility of improving the processing of neem flakes in columns by performing the leaching of insecticide without intermediate removal of the non-polar solvent and by performing simultaneously both leaching steps. ...
In this study, a mathematical model to simulate the drying of rough rice in a continuous plug-flo... more In this study, a mathematical model to simulate the drying of rough rice in a continuous plug-flow fluidised bed dryer ispresented. Equipment and material models were applied to describe the process. The equipment model was based on thedifferential equations obtained by applying mass and energy balances to each element of the dryer. Concerning the materialmodel, mass and heat transfer rates in a single isolated particle were considered. Mass and heat transfer within the particles wasdescribed by analytical solutions with constant effective transport coefficients. To simulate the dryer, the material model wasimplemented in the equipment model in order to describe the whole process. Calculation results were verified by comparisonwith experimental data from the literature. There was very good agreement between experimental data and simulation. Theeffects of gas temperature and velocity, particle diameter, dry solid flow and solid temperature on the drying process wereinvestigated. It w...
An experimental study was carried out to determine the effect of strontium (Sr) on the characteri... more An experimental study was carried out to determine the effect of strontium (Sr) on the characteristic of intermetallic phases, particularly the Al5FeSi phase which present morphology of platelets or needle-like. The results showed that within the range of variables studied, the modification process caused the disappearance of the needles and only occur the precipitation of phase α (chinese script-like). Refinement of the intermetallic phases occurs in conjunction with the refinement in grain size. Both parameters depend strongly on local cooling rate (T), temperature gradient (G) and apparent rate of solidification front (V). In the case of equiaxed structures the refinement of grain size and intermetallic occurs with increasing local cooling rate and temperature gradient and decrease the apparent rate of solidification front. In the case of columnar structures, refinement of grains and intermetallic requires the increase in values of the three variables indicated. Moreover, the add...
&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;El objet... more &amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;El objetivo de este trabajo es estudiar experimentalmente la viabilidad de mejorar el procesamiento de hojuelas de nim en columnas, mediante la realización de la lixiviación del insecticida sin la remoción intermedia del solvente no-polar; y mediante la simultánea realización de ambas etapas de lixiviación. El secado de los solventes remanentes en las hojuelas de nim también se estudió experimentalmente. En la parte de lixiviación, los parámetros estudiados fueron tiempo de lixiviación, grosor de hojuelas, relación de volumen de solventes y volumen total de solventes. Estos parámetros mostraron tener una gran influencia en el rendimiento de los compuestos insecticidas, pero la influencia de la relación de solventes fue la más importante. Se demostró que más metanol que hexano tuvo que ser empleado para obtener un mayor rendimiento de compuestos insecticidas. El rendimiento de aceite fue influenciado principalmente por el grosor de las hojuelas. En la parte de secado, la temperatura del flujo de aire entrante tiene influencia en el proceso. Conclusiones sobre el tiempo de secado o la velocidad de secado no son posibles de realizar a partir de los resultados de los experimentos. Las variaciones en el tiempo de secado son demasiadas grandes y la velocidad de secado parece ser independiente de las condiciones de la etapa de lixiviación anterior.&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;
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