Numerical Study of a High Temperature Latent Heat Storage (200-300 0 C) Using Eutectic Nitrate Salt of Sodium Nitrate and Potassium Nitrate

Abstract: In this study, a small scale direct solar thermal energy storage unit for a parabolic dish system with a secondary reflector is designed and developed. The main advantage of thermal energy storage is that thermal energy is available also during times when there is little or no sun shine. In addition, no heat transport fluid is needed in this system. A well insulated heat storage should keep the heat for about 24 hours. KNO 3 and NaNO 3 in 60:40 percent ratio (mol %) is used as latent heat storage material (PCM). This type of salt is also used in large scale solar power plants producing electricity. Effects of the heat flux and the number of fins on the latent heat storage charging process were numerically simulated using COMSOL Multiphysics. During phase change (melting) of the PCM, large amount of energy in the form of latent heat of fusion is needed. The phase change heat transfer was implemented using the effective heat capacity method

Have medical students’ attitudes towards clinical communication skills changed over a 12- year period? A comparative long-term study

Background Attitudes towards learning clinical communication skills at the end of medical school are likely to reflect the students’ training and motivation for the continued development of their skills as doctors. Students from two Norwegian medical schools, one with a traditional, and the other with an integrated curriculum, were approached in 2003 and 2015; with regard to changes in students’ attitudes towards acquiring communication skills in two diverse learning environments. This comparison might reveal the effects of the training programs from a long-term perspective, as neither of the medical schools made any major curriculum changes within the study period. Methods The samples comprised final-year medical students. Two separate cross-sectional surveys performed 12 years apart (2003 and 2015) used items from the Communication Skills Attitude Scale in addition to age and gender. The traditional curriculum included only theoretical teaching and no contact with patients was made during the first 2 to 2.5 years of medical school. However, the integrated curriculum combined training in theoretical and clinical communication skills with early patient contact from the beginning. Results Attitudes improved from the first to the second survey at both schools, however, students from the integrated school reported more positive attitudes than those from the traditional school. Female students from the integrated school contributed the most to the difference in attitudes in both surveys. Conclusions Students in both traditional and integrated curricula improved their attitudes from the first to the second assessment. However, compared with the traditional curriculum, the integrated one fostered even higher levels of positive attitudes towards acquiring communication skills, and a pronounced influence was observed on female students. These findings suggest that an educational program with greater emphasis on improving attitudes among male students may be required.publishedVersio

A solar energy resources assessment in Mozambique

Just as with other Southern African Development Community (SADC) countries, Mozambique faces severe, interrelated problems of energy and environment linked, with massive consumption of fuel wood biomass. The conventional power grid provides less than 7% of the energy needs for the country's 17 million inhabitants, and about 83% of the energy consumed in the country comes from biomass. Renewable energy resources can play an important role in the process of development of the country. From the vast renewable energy resources available in the country, solar energy represents one of those with the highest potential. Thus, the evaluation of the potential of solar energy systems in small-scale applications suitable for villages is a strategically good starting point for promotion of sustainable rural development. One of the major impediments In carrying out such studies is the fact that the exact behaviour of solar energy resources throughout the country has not been well studied. In this paper a general characterisation of the global, diffuse and direct solar radiation fields in Mozambique Is presented. The study Is based on experimental data measured by the National Institute of Meteorology (INAM) In the period 1970-2000. For these analyses global, diffuse and direct solar radiation data from three stations along the coast line and three stations in the interior of the country have been used. The six stations were representative of the three main regions of the country, namely south, centre and north. Furthermore, sunshine hours data of one selected station was analysed

General characterisation of the solar radiation components in Mozambique

Just as with the other Southern African Development Community (SADC) countries, Mozambique faces severe and interrelated problems of energy and environment linked with the massive consumption of fuel wood biomass. The conventional power grid provides less than 7% of the energy needs for the country's 17 million inhabitants, and about 83% of the energy consumed in the country comes from biomass. Areas around the major urban centres and along the main development corridors are the most affected by energy shortages. This hinders the country's economic and social development as it is generally acknowledged that no development can be sustainable without linking it to energy planning and environmental management. Renewable energy resources can play an important role in the process of development of the country. From the vast renewable energy resources available in the country, solar energy represents one of those with the highest potential. Thus the evaluation of the potential of solar energy systems in small-scale applications suitable for villages is a strategically good starting point for promotion of a sustainable rural development. One of the major impediments in carrying out such studies is the fact that the exact behaviour of solar energy resources throughout the country has not been well studied yet. In this paper a general characterisation of the global, diffuse and direct solar radiation fields in Mozambique is presented. The study is based on experimental data measured by the National Institute of Meteorology (INAM) in the period 1970-2000. Data from 11 stations recording global solar radiation, from 6 stations measuring diffuse solar radiation, as well as data from 80 sunshine hours stations have been used for this work. For this purpose the country has been divided into four main climate zones. The northern and coastal regions, representing 60% of the total surface of the country, have a tropical rain savanna climate. The inland parts of the central and southern edimentary terrains, with a share of 28%, have a dry savanna climate. A small area around the border crossing of the Limpopo River, representing 2% of the country's surface, has a dry desert climate, whereas the upland areas, with a share of 10%, have a humid temperate climate. Results of the present work reveal that the country has substantial solar energy resources for a variety of solar energy technologies. Areas with the dry savanna and dry desert climates, representing in total around 30% of the country's surface are particularly appropriate for dense placement of solar energy technologies

Have medical students’ attitudes towards clinical communication skills changed over a 12- year period? A comparative long-term study

Background Attitudes towards learning clinical communication skills at the end of medical school are likely to reflect the students’ training and motivation for the continued development of their skills as doctors. Students from two Norwegian medical schools, one with a traditional, and the other with an integrated curriculum, were approached in 2003 and 2015; with regard to changes in students’ attitudes towards acquiring communication skills in two diverse learning environments. This comparison might reveal the effects of the training programs from a long-term perspective, as neither of the medical schools made any major curriculum changes within the study period. Methods The samples comprised final-year medical students. Two separate cross-sectional surveys performed 12 years apart (2003 and 2015) used items from the Communication Skills Attitude Scale in addition to age and gender. The traditional curriculum included only theoretical teaching and no contact with patients was made during the first 2 to 2.5 years of medical school. However, the integrated curriculum combined training in theoretical and clinical communication skills with early patient contact from the beginning. Results Attitudes improved from the first to the second survey at both schools, however, students from the integrated school reported more positive attitudes than those from the traditional school. Female students from the integrated school contributed the most to the difference in attitudes in both surveys. Conclusions Students in both traditional and integrated curricula improved their attitudes from the first to the second assessment. However, compared with the traditional curriculum, the integrated one fostered even higher levels of positive attitudes towards acquiring communication skills, and a pronounced influence was observed on female students. These findings suggest that an educational program with greater emphasis on improving attitudes among male students may be required