Ernesto Marin | Instituto Politécnico Nacional (original) (raw)
Papers by Ernesto Marin
Respuestas, 2016
Reportamos el uso de la técnica fotoacústica resuelta en tiempo en el análisis de la evolución de... more Reportamos el uso de la técnica fotoacústica resuelta en tiempo en el análisis de la evolución de oxígeno fotosintético y el almacenamiento de energía en plantas verdes. Presentamos una aplicación de esta técnica al monitoreo de la fotosíntesis en la maleza acuática llamada comúnmente lirio acuático o jacinto de agua (Eichhornia Crassipes).Palabras Clave: Fotosíntesis; técnica fotoacústica; lirio acuáticoWe reported about the use of the time resolved photoacoustic technique for the analysis of the photosynthetic oxygen evolution and the energy storage in green plants. We present an application of this technique to the study of the photosynthesis in the aquatic vegetation, usually called aquatic lirium or water hyacinth (Eichhornia Crassipes). Keywords: Photosynthesis, photoacoustic technique, water hyacinth.
European Journal of Physics, 2021
Starting from a brief review on the concepts of electrical resistance and impedance and the defin... more Starting from a brief review on the concepts of electrical resistance and impedance and the definition of thermal resistance, it is shown how thermal impedance can be defined from a simple situation of an ideal semi-infinite solid sample subjected to uniform sinusoidal heating at its surface. Using the thermal impedance definition, the non-stationary component of the temperature field perpendicular to the surface of the sample can be rewritten in a more compact form than as usual. It is shown that a dimensionless number dependent on thermal impedance can be defined for non-stationary phenomena to compare the efficiency between the different modes of heat transfer. The thermal impedance concept for the little-known for most people (but not least important) case of non-Fourier heat conduction is also discussed here. We show that the thermal impedance for diffusive Fourier heat transfer is a complex valued parameter with the same real and imaginary parts. However, this behavior is affected when approaching non-Fourier conditions, under which the imaginary component can become a pure imaginary parameter. These topics are not treated in heat transfer and physics textbooks. However, the subject can be of interest not only for students and teachers at undergraduate and graduate levels but also for scientists dealing with heat transfer in the presence of time-varying periodical heat sources.
MRS Proceedings, 2009
ABSTRACTIn this work we report about the design and construction of a simple and cheap calorimete... more ABSTRACTIn this work we report about the design and construction of a simple and cheap calorimeter for phase transitions monitoring using Peltier elements and based in the well known inverse (front) photopyroelectric method for thermophysical characterization of materials. We describe its application for the detection of phase transitions in chocolate samples, as an alternative, for example, to the most widely used and more expensive Differential Scanning Calorimetry technique. The manufacture of chocolate requires an understanding of the chemistry and the physical properties of the product. Thus the involved problems during the confection process are those of the so-called materials science. Among them, those related with tempering are of particular importance. Because the fats in cocoa butter experience the so-called polymorphous crystallization, the primary purpose of tempering is to assure that only the best form is present in the final product. One way to characterize this is b...
Open Physics, 2010
We show that the front photoacoustic signal due to a sample consisting of a glass plate with a me... more We show that the front photoacoustic signal due to a sample consisting of a glass plate with a metal coated surface, at which thermal waves are generated by periodical light absorption, enhances for certain modulation frequencies when the other glass surface is covered with a liquid sample. This contradicts the intuitive expectation based on the assumption that the liquid provides a new channel for heat conduction thereby decreasing the substrate temperature. Experimental results are shown and the described effect is explained using a thermal wave interference model.
Journal of Materials Science, 2011
In this paper a new and practical model for the determination of transport parameters of crystall... more In this paper a new and practical model for the determination of transport parameters of crystalline semiconductors, by means of the photoacoustic technique is reported. The model is based on the calculation of the photoacoustic signal for the so-called heat transmission configuration, and considers that the thermal response to periodical heating, due to light absorption, in semiconductor materials has mainly two contributions: (a) the vibrations of the crystal lattice (phonon contribution) and (b) the diffusion and recombination (bulk and superficial) of the photogenerated charge carriers. Considering these contributions as the heat sources, and using unmixed Dirichlet and Neumann boundary conditions, the solution of the heat diffusion equation, necessary for the calculation of the photoacoustic signal is obtained. In addition, an expression-describing a particular transport regime-that can be used as practical fitting function, for the more available experimental conditions, is developed. Finally, values of transport parameters for silicon wafers are obtained by fitting this model to the experimental data, showing a good agreement with the values quoted in literature.
International Journal of Thermophysics, 2006
This paper is related to the well known thermal relaxation method for measurement of the specific... more This paper is related to the well known thermal relaxation method for measurement of the specific heat of thin solid samples. Although this method was applied successfully in the last years for the characterization of different materials, in this work we will discuss some aspects that must be taken into account in order to avoid failure to meet experimentally the required conditions of heat flux imposed by the physical model used for data analysis and processing. For this purpose, for a given experimental geometry, we will solve the heat diffusion equation in order to obtain the sample's requirements for reliable measurements of C, regarding its thickness and thermal conductivity. An experimental device is described allowing the study of the influence on the method of heat dissipation by convection. A computer simulation was performed for comparing the simple common model with one that takes in to account the gradient of temperature inside the sample. The results of our measurements are presented.
Sistema automatizado para la medición de la conductividad térmica de líquidos mediante el método ... more Sistema automatizado para la medición de la conductividad térmica de líquidos mediante el método del alambre caliente. Manakin: DSpace XMLUI Project v2. ...
Journal de Physique IV (Proceedings), 2005
We discuss the influence of convection and conduction on the temperature relaxation method to mea... more We discuss the influence of convection and conduction on the temperature relaxation method to measure the specific heat capacity at constant pressure of solids at room temperature.
Journal de Physique IV (Proceedings), 2005
European Journal of Physics, 2012
ABSTRACT The implementation of an automated system based on the hot-wire technique is described f... more ABSTRACT The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer and a high purity platinum wire). The wire, which is immersed in the investigated sample, is heated by passing a constant electrical current through it, and its temperature evolution, ΔT, is measured as a function of time, t, for several values of the current. A straightforward methodology is then used for data processing in order to obtain the liquid thermal conductivity. The start point is the well known linear relationship between ΔT and ln(t) predicted for long heating times by a model based on a solution of the heat conduction equation for an infinite lineal heat source embedded in an infinite medium into which heat is conducted without convective and radiative heat losses. A criterion is used to verify that the selected linear region is the one that matches the conditions imposed by the theoretical model. As a consequence the method involves least-squares fits in linear, semi-logarithmic (semi-log) and log–log graphs, so that it becomes attractive not only to teach about heat transfer and thermal properties measurement techniques, but also as a good exercise for students of undergraduate courses of physics and engineering learning about these kinds of mathematical functional relationships between variables. The functionality of the experiment was demonstrated by measuring the thermal conductivity in samples of liquids with well known thermal properties.
Fundamental and applied research have instigated and still require today the development of metho... more Fundamental and applied research have instigated and still require today the development of methods for studying phenomena and measurement of properties in several fields of science. In this introductory chapter we will examine the basic principles of a whole range of methods based on the common principle of heating the sample with intensity modulated or pulsed radiation beams and measuring the resulting dynamical sample's temperature (often denoted as thermal waves) or the fluctuations of some temperature dependent parameter, i.e., the so-called photothermal techniques.
We applied the Hot Wire (HW) technique and COMSOL Multiphysics software to study the heat transfe... more We applied the Hot Wire (HW) technique and COMSOL Multiphysics software to study the heat transfer of a homogeneous and isotropic solid material. The HW technique is based on the application of a linear power density modulated by a square pulse of heat in a specific time period. The power density is applied over the symmetry axis of the sample to produce a radial heat flux and then, to determine the thermophysical properties like specific heat, thermal conductivity and thermal diffusivity. In this work, the solutions of the transient heat transport equation by means of the finite element technique with appropriate boundary conditions are reported. Finally, we compared our simulated results with the experimental ones and some approximate mathematical models with a good agreement. These results show the utility of this methodology in the study of thermal properties in solids.
Respuestas, 2016
Reportamos el uso de la técnica fotoacústica resuelta en tiempo en el análisis de la evolución de... more Reportamos el uso de la técnica fotoacústica resuelta en tiempo en el análisis de la evolución de oxígeno fotosintético y el almacenamiento de energía en plantas verdes. Presentamos una aplicación de esta técnica al monitoreo de la fotosíntesis en la maleza acuática llamada comúnmente lirio acuático o jacinto de agua (Eichhornia Crassipes).Palabras Clave: Fotosíntesis; técnica fotoacústica; lirio acuáticoWe reported about the use of the time resolved photoacoustic technique for the analysis of the photosynthetic oxygen evolution and the energy storage in green plants. We present an application of this technique to the study of the photosynthesis in the aquatic vegetation, usually called aquatic lirium or water hyacinth (Eichhornia Crassipes). Keywords: Photosynthesis, photoacoustic technique, water hyacinth.
European Journal of Physics, 2021
Starting from a brief review on the concepts of electrical resistance and impedance and the defin... more Starting from a brief review on the concepts of electrical resistance and impedance and the definition of thermal resistance, it is shown how thermal impedance can be defined from a simple situation of an ideal semi-infinite solid sample subjected to uniform sinusoidal heating at its surface. Using the thermal impedance definition, the non-stationary component of the temperature field perpendicular to the surface of the sample can be rewritten in a more compact form than as usual. It is shown that a dimensionless number dependent on thermal impedance can be defined for non-stationary phenomena to compare the efficiency between the different modes of heat transfer. The thermal impedance concept for the little-known for most people (but not least important) case of non-Fourier heat conduction is also discussed here. We show that the thermal impedance for diffusive Fourier heat transfer is a complex valued parameter with the same real and imaginary parts. However, this behavior is affected when approaching non-Fourier conditions, under which the imaginary component can become a pure imaginary parameter. These topics are not treated in heat transfer and physics textbooks. However, the subject can be of interest not only for students and teachers at undergraduate and graduate levels but also for scientists dealing with heat transfer in the presence of time-varying periodical heat sources.
MRS Proceedings, 2009
ABSTRACTIn this work we report about the design and construction of a simple and cheap calorimete... more ABSTRACTIn this work we report about the design and construction of a simple and cheap calorimeter for phase transitions monitoring using Peltier elements and based in the well known inverse (front) photopyroelectric method for thermophysical characterization of materials. We describe its application for the detection of phase transitions in chocolate samples, as an alternative, for example, to the most widely used and more expensive Differential Scanning Calorimetry technique. The manufacture of chocolate requires an understanding of the chemistry and the physical properties of the product. Thus the involved problems during the confection process are those of the so-called materials science. Among them, those related with tempering are of particular importance. Because the fats in cocoa butter experience the so-called polymorphous crystallization, the primary purpose of tempering is to assure that only the best form is present in the final product. One way to characterize this is b...
Open Physics, 2010
We show that the front photoacoustic signal due to a sample consisting of a glass plate with a me... more We show that the front photoacoustic signal due to a sample consisting of a glass plate with a metal coated surface, at which thermal waves are generated by periodical light absorption, enhances for certain modulation frequencies when the other glass surface is covered with a liquid sample. This contradicts the intuitive expectation based on the assumption that the liquid provides a new channel for heat conduction thereby decreasing the substrate temperature. Experimental results are shown and the described effect is explained using a thermal wave interference model.
Journal of Materials Science, 2011
In this paper a new and practical model for the determination of transport parameters of crystall... more In this paper a new and practical model for the determination of transport parameters of crystalline semiconductors, by means of the photoacoustic technique is reported. The model is based on the calculation of the photoacoustic signal for the so-called heat transmission configuration, and considers that the thermal response to periodical heating, due to light absorption, in semiconductor materials has mainly two contributions: (a) the vibrations of the crystal lattice (phonon contribution) and (b) the diffusion and recombination (bulk and superficial) of the photogenerated charge carriers. Considering these contributions as the heat sources, and using unmixed Dirichlet and Neumann boundary conditions, the solution of the heat diffusion equation, necessary for the calculation of the photoacoustic signal is obtained. In addition, an expression-describing a particular transport regime-that can be used as practical fitting function, for the more available experimental conditions, is developed. Finally, values of transport parameters for silicon wafers are obtained by fitting this model to the experimental data, showing a good agreement with the values quoted in literature.
International Journal of Thermophysics, 2006
This paper is related to the well known thermal relaxation method for measurement of the specific... more This paper is related to the well known thermal relaxation method for measurement of the specific heat of thin solid samples. Although this method was applied successfully in the last years for the characterization of different materials, in this work we will discuss some aspects that must be taken into account in order to avoid failure to meet experimentally the required conditions of heat flux imposed by the physical model used for data analysis and processing. For this purpose, for a given experimental geometry, we will solve the heat diffusion equation in order to obtain the sample's requirements for reliable measurements of C, regarding its thickness and thermal conductivity. An experimental device is described allowing the study of the influence on the method of heat dissipation by convection. A computer simulation was performed for comparing the simple common model with one that takes in to account the gradient of temperature inside the sample. The results of our measurements are presented.
Sistema automatizado para la medición de la conductividad térmica de líquidos mediante el método ... more Sistema automatizado para la medición de la conductividad térmica de líquidos mediante el método del alambre caliente. Manakin: DSpace XMLUI Project v2. ...
Journal de Physique IV (Proceedings), 2005
We discuss the influence of convection and conduction on the temperature relaxation method to mea... more We discuss the influence of convection and conduction on the temperature relaxation method to measure the specific heat capacity at constant pressure of solids at room temperature.
Journal de Physique IV (Proceedings), 2005
European Journal of Physics, 2012
ABSTRACT The implementation of an automated system based on the hot-wire technique is described f... more ABSTRACT The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer and a high purity platinum wire). The wire, which is immersed in the investigated sample, is heated by passing a constant electrical current through it, and its temperature evolution, ΔT, is measured as a function of time, t, for several values of the current. A straightforward methodology is then used for data processing in order to obtain the liquid thermal conductivity. The start point is the well known linear relationship between ΔT and ln(t) predicted for long heating times by a model based on a solution of the heat conduction equation for an infinite lineal heat source embedded in an infinite medium into which heat is conducted without convective and radiative heat losses. A criterion is used to verify that the selected linear region is the one that matches the conditions imposed by the theoretical model. As a consequence the method involves least-squares fits in linear, semi-logarithmic (semi-log) and log–log graphs, so that it becomes attractive not only to teach about heat transfer and thermal properties measurement techniques, but also as a good exercise for students of undergraduate courses of physics and engineering learning about these kinds of mathematical functional relationships between variables. The functionality of the experiment was demonstrated by measuring the thermal conductivity in samples of liquids with well known thermal properties.
Fundamental and applied research have instigated and still require today the development of metho... more Fundamental and applied research have instigated and still require today the development of methods for studying phenomena and measurement of properties in several fields of science. In this introductory chapter we will examine the basic principles of a whole range of methods based on the common principle of heating the sample with intensity modulated or pulsed radiation beams and measuring the resulting dynamical sample's temperature (often denoted as thermal waves) or the fluctuations of some temperature dependent parameter, i.e., the so-called photothermal techniques.
We applied the Hot Wire (HW) technique and COMSOL Multiphysics software to study the heat transfe... more We applied the Hot Wire (HW) technique and COMSOL Multiphysics software to study the heat transfer of a homogeneous and isotropic solid material. The HW technique is based on the application of a linear power density modulated by a square pulse of heat in a specific time period. The power density is applied over the symmetry axis of the sample to produce a radial heat flux and then, to determine the thermophysical properties like specific heat, thermal conductivity and thermal diffusivity. In this work, the solutions of the transient heat transport equation by means of the finite element technique with appropriate boundary conditions are reported. Finally, we compared our simulated results with the experimental ones and some approximate mathematical models with a good agreement. These results show the utility of this methodology in the study of thermal properties in solids.