Documents disponibles écrits par cet auteur

Analysis and design of a paraffin/graphite composite PCM integrated in a thermal storage unit / R. Pokhrel in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041006/1-8] Titre : Analysis and design of a paraffin/graphite composite PCM integrated in a thermal storage unit Type de document : texte imprimé Auteurs : R. Pokhrel, Auteur ; J. E. Gonzalez, Auteur ; T. Hight, Auteur Année de publication : 2011 Article en page(s) : pp. [041006/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Composite  materials  Differential  scanning  calorimetry  Graphite  Latent  heat  Melting  Phase  change  materials  Solidification  Thermal  conductivity  Thermal  energy  storage Résumé : The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Analysis and design of a paraffin/graphite composite PCM integrated in a thermal storage unit [texte imprimé] / R. Pokhrel, Auteur ; J. E. Gonzalez, Auteur ; T. Hight, Auteur . - 2011 . - pp. [041006/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041006/1-8] Mots-clés : Composite  materials  Differential  scanning  calorimetry  Graphite  Latent  heat  Melting  Phase  change  materials  Solidification  Thermal  conductivity  Thermal  energy  storage Résumé : The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Impacts of climate change in degree days and energy demand in coastal California / B. Lebassi in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 3 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031005/1-9] Titre : Impacts of climate change in degree days and energy demand in coastal California Type de document : texte imprimé Auteurs : B. Lebassi, Auteur ; J. E. Gonzalez, Auteur ; D. Fabris, Auteur Année de publication : 2011 Article en page(s) : pp. [031005/1-9] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Climatology  Meteorology  Power  stations Index. décimale : 621.47 Résumé : An analysis of 1970–2005 observed summer daily maximum and minimum temperatures in two California air basins showed concurrent daytime coastal cooling and inland warming. To study the impacts of these results on energy consumption, summer cooling degree day (CDD) and winter heating degree day (HDD) trends were analyzed via these temperatures. The 2 m level air temperatures consisted of data from 159 locations in California, each with daily minimum and maximum values. Primary data sources included Cooperative Weather Station Network sites, first order National Weather Service stations, and military weather stations. An analysis of the CDD and HDD data has been undertaken for California, in general, and the San Francisco Bay Area and South Coast Air Basin, in particular, as the source of data for an analysis of energy-demand trends. Regional climate fluctuations have considerable effects on surface temperatures, which in turn affect CDD and HDD values. An asymmetric increase in summer CDD values between coastal and inland regions of California was found during the last 35 years, while winter HDD values showed decreases in most of California. In general, coastal areas experienced decreases of CDD, while inland regions experienced increases. The summer asymmetric increases in CDD is attributed to intensified sea breeze flows, which suggests increases in cold marine air intrusions over coastal land masses due to an increased regional sea breeze potential, which ventilates coastal areas, helps reduce maximum temperatures, and contributes to CDD decreases. An analysis of energy demands in the two air basins supports these climatological findings. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Impacts of climate change in degree days and energy demand in coastal California [texte imprimé] / B. Lebassi, Auteur ; J. E. Gonzalez, Auteur ; D. Fabris, Auteur . - 2011 . - pp. [031005/1-9]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031005/1-9] Mots-clés : Climatology  Meteorology  Power  stations Index. décimale : 621.47 Résumé : An analysis of 1970–2005 observed summer daily maximum and minimum temperatures in two California air basins showed concurrent daytime coastal cooling and inland warming. To study the impacts of these results on energy consumption, summer cooling degree day (CDD) and winter heating degree day (HDD) trends were analyzed via these temperatures. The 2 m level air temperatures consisted of data from 159 locations in California, each with daily minimum and maximum values. Primary data sources included Cooperative Weather Station Network sites, first order National Weather Service stations, and military weather stations. An analysis of the CDD and HDD data has been undertaken for California, in general, and the San Francisco Bay Area and South Coast Air Basin, in particular, as the source of data for an analysis of energy-demand trends. Regional climate fluctuations have considerable effects on surface temperatures, which in turn affect CDD and HDD values. An asymmetric increase in summer CDD values between coastal and inland regions of California was found during the last 35 years, while winter HDD values showed decreases in most of California. In general, coastal areas experienced decreases of CDD, while inland regions experienced increases. The summer asymmetric increases in CDD is attributed to intensified sea breeze flows, which suggests increases in cold marine air intrusions over coastal land masses due to an increased regional sea breeze potential, which ventilates coastal areas, helps reduce maximum temperatures, and contributes to CDD decreases. An analysis of energy demands in the two air basins supports these climatological findings. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Implementing motivational features in reactive blended learning / Mendez, J.A. in IEEE transactions on education, Vol. 54 N° 4 (Novembre 2011) 

Public ISBD [article]  in IEEE transactions on education > Vol. 54 N° 4 (Novembre 2011) . - pp. 619 - 627 Titre : Implementing motivational features in reactive blended learning : application to an introductory control engineering course Type de document : texte imprimé Auteurs : Mendez, J.A., Auteur ; J. E. Gonzalez, Auteur Année de publication : 2013 Article en page(s) : pp. 619 - 627 Note générale : education Langues : Français (fre) Mots-clés : applications  in  subject  areas;  classroom  teaching;  distance  education;  simulations;  teaching/learning  strategies;  telelearning Résumé : This paper presents a significant advance in a reactive blended learning methodology applied to an introductory control engineering course. This proposal was based on the inclusion of a reactive element (a fuzzy-logic-based controller) designed to regulate the workload for each student according to his/her activity and performance. The contribution of this proposal stands on the inclusion of elements related to motivational factors in the students. Student motivation has been widely identified as a key factor for the academic success of every teaching-learning activity. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5685599&sortType%3Das [...] [article] Implementing motivational features in reactive blended learning : application to an introductory control engineering course [texte imprimé] / Mendez, J.A., Auteur ; J. E. Gonzalez, Auteur . - 2013 . - pp. 619 - 627. education Langues : Français (fre) in IEEE transactions on education > Vol. 54 N° 4 (Novembre 2011) . - pp. 619 - 627 Mots-clés : applications  in  subject  areas;  classroom  teaching;  distance  education;  simulations;  teaching/learning  strategies;  telelearning Résumé : This paper presents a significant advance in a reactive blended learning methodology applied to an introductory control engineering course. This proposal was based on the inclusion of a reactive element (a fuzzy-logic-based controller) designed to regulate the workload for each student according to his/her activity and performance. The contribution of this proposal stands on the inclusion of elements related to motivational factors in the students. Student motivation has been widely identified as a key factor for the academic success of every teaching-learning activity. En ligne : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5685599&sortType%3Das [...]

The impacts of climate changes on the renewable energy resources in the Caribbean region / M. E. Angeles in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 3 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031009/1-13] Titre : The impacts of climate changes on the renewable energy resources in the Caribbean region Type de document : texte imprimé Auteurs : M. E. Angeles, Auteur ; J. E. Gonzalez, Auteur ; D. J. Erickson III, Auteur Année de publication : 2011 Article en page(s) : pp. [031009/1-13] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : IPCC  PCM  RAMS  Climate  change  Future  Caribbean  insolation  Future  Caribbean  wind  speed Index. décimale : 621.47 Résumé : Assessment of renewable energy resources such as surface solar radiation and wind current has great relevance in the development of local and regional energy policies. This paper examines the variability and availability of these resources as a function of possible climate changes for the Caribbean region. Global climate changes have been reported in the last decades, causing changes in the atmospheric dynamics, which affects the net solar radiation balance at the surface and the wind strength and direction. For this investigation, the future climate changes for the Caribbean are predicted using the parallel climate model (PCM) and it is coupled with the numerical model regional atmospheric modeling system (RAMS) to simulate the solar and wind energy spatial patterns changes for the specific case of the island of Puerto Rico. Numerical results from PCM indicate that the Caribbean basin from 2041 to 2055 will experience a slight decrease in the net surface solar radiation (with respect to the years 1996–2010), which is more pronounced in the western Caribbean sea. Results also indicate that the easterly winds have a tendency to increase in its magnitude, especially from the years 2070 to 2098. The regional model showed that important areas to collect solar energy are located in the eastern side of Puerto Rico, while the more intense wind speed is placed around the coast. A future climate change is expected in the Caribbean that will result in higher energy demands, but both renewable energy sources will have enough intensity to be used in the future as alternative energy resources to mitigate future climate changes. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] The impacts of climate changes on the renewable energy resources in the Caribbean region [texte imprimé] / M. E. Angeles, Auteur ; J. E. Gonzalez, Auteur ; D. J. Erickson III, Auteur . - 2011 . - pp. [031009/1-13]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031009/1-13] Mots-clés : IPCC  PCM  RAMS  Climate  change  Future  Caribbean  insolation  Future  Caribbean  wind  speed Index. décimale : 621.47 Résumé : Assessment of renewable energy resources such as surface solar radiation and wind current has great relevance in the development of local and regional energy policies. This paper examines the variability and availability of these resources as a function of possible climate changes for the Caribbean region. Global climate changes have been reported in the last decades, causing changes in the atmospheric dynamics, which affects the net solar radiation balance at the surface and the wind strength and direction. For this investigation, the future climate changes for the Caribbean are predicted using the parallel climate model (PCM) and it is coupled with the numerical model regional atmospheric modeling system (RAMS) to simulate the solar and wind energy spatial patterns changes for the specific case of the island of Puerto Rico. Numerical results from PCM indicate that the Caribbean basin from 2041 to 2055 will experience a slight decrease in the net surface solar radiation (with respect to the years 1996–2010), which is more pronounced in the western Caribbean sea. Results also indicate that the easterly winds have a tendency to increase in its magnitude, especially from the years 2070 to 2098. The regional model showed that important areas to collect solar energy are located in the eastern side of Puerto Rico, while the more intense wind speed is placed around the coast. A future climate change is expected in the Caribbean that will result in higher energy demands, but both renewable energy sources will have enough intensity to be used in the future as alternative energy resources to mitigate future climate changes. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]