Numerical analysis of a modified evacuated tubes solar collector

The need for renewable energy sources, facing the consequences of Climate Change, results in growing investment for solar collectors’ use. Research in this field has accompanied this expansion and evacuated tube solar collector stands as an important study focus. Thus, several works have been published for representing the stratification of the fluid inside the tubes and the reservoir, as well as analytical modeling for the heat flow problem. Based on recent publications, this paper proposes the study of solar water heating with evacuated tubes, their operation characteristics and operating parameters. To develop this work, a computational tool will be used - in this case, the application of computational fluid dynamics (CFD) software. In possession of the implemented model, a numerical simulation will be performed to evaluate the behavior of the fluid within this solar collector and possible improvements to be applied in the model.

Analisys of thermal efficiency of a modified solar collector type evacuated tube

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise numérica de uma geometria de coletor solar para sistemas de aquecimento de água

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise numérica de um sistema integrado coletor solar/armazenador térmico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Feasibility of solar heating systems composed of recyclable packaging for low-income rural communities

Solar heaters are an appropriate technology in tropical and sub-tropical climates to heat bath water by solar energy. Low-cost solar heaters meet the demand of low-income rural communities which currently do not have access to this technology. Current research analyzes the economic viability of solar heaters, built with recyclable materials, to reduce electric energy bill. A solar heating system was built consisting of recyclable materials in accordance with the manuals provided by the Secretariat of Environment of the state of Paraná (SEMA). Duration of use of electric showers by families of rural properties was determined to calculate expenses and billing of electricity. Simulation and material costs showed that the system was feasible. Commercial solar heaters could be replaced at a cost of R$ 22.61 per month during 13 months.

Análise diferencial da potência máxima gerada por um sistema solar fotovoltaico

The Earth receives annually 1,5.1018 kWh of solar energy, which corresponds to 1000 times the world energy consumption in this period. This fact comes out that, besides being responsible for the maintenance of life on Earth, the solar radiation is in an inexhaustible energy source, with an enormous potential for use by systems capture and conversion into another form of energy. In many applications of low power systems that convert light directly into electricity, called photovoltaic advantageously replace other means of production processes, where its distribution is very significant. The determination of the power generated by such a system is of paramount importance for the design energy of its implementation and evaluation of the system itself. This study aims to determine a relationship between the maximum power generated by solar photovoltaic and characteristic parameters of the generator. This relationship allows to evaluate the performance of such a system. For simulations of the developed equations were used 3 photovoltaic modules with an output of 100 Wp each, and data collection was performed during one year by enrolling in addition to meteorological data, solar irradiance incident on the modules.

Diurnal evolution of the hourly diffuse solar radiation incident on tilted surfaces in Southeast of Brazil

Evaluation has been made on the monthly and annual average diurnal evolution of the hourly diffuse radiation as well as its radiometric fractions on surfaces inclined at 12.85, 22.85 and 32.85° to face North, in climate conditions of Botucatu, São Paulo, Brazil (22.85° S and 48.43° W). Measurements were made between 04/1998 to 08/2001 for 22.85°; 09/2001 to 02/2003 for 12.85° and 01/2004 to 12/2007 for 32.85°, with concomitant measures in the horizontal. For all surfaces the diffuse radiation was obtained from different method. Assessment has been performed as well on the radiometric fractions obtained from the ratio of diffuse radiation and global radiation (KDH and KDβ) and between radiation and diffuse radiation at the top of the atmosphere (KʹDH and KʹDβ) for the horizontal and tilted surfaces in hourly partition. The diffuse radiation levels were dependent on variations in precipitation and cloudiness. There was an increase in the differences between the diffuse radiation and the radiometric fractions with the increment of the angle, and in horizontally, which affected higher levels of diffuse radiation in spring and summer. The values of KDH and KDβ present in an inverse behavior were compared to diffuse radiation and theydecreased in the southern passage due to the increase of the direct component in the total of incident radiation.

Sistema autônomo de iluminação utilizando energia solar

This work presents a self-sustainable lighting system using ultracapacitor as a storage device, replacing the conventional battery, using solar energy as the only energy supplier. A detailed study of solar panels, switched mode converters and ultracapacitors was made, in order to design a circuit capable of capturing solar energy and transfer it efficiently to a bank of ultracapacitors. Later, at nighttime, this energy is used for lighting in LED luminaires which have high luminous efficiency and high reliability index. This work presents the design of the solar panel, ultracapacitors bank, the development of the voltage converter circuit and charger working at the maximum power point of the solar panel. All subsystems were simulated and it was shown that the use of ultracapacitors is feasible to feed a LED lamp with enough brightness for a person to walk at night, for two night shifts, using a capacitive bank with twenty-four ultracapacitors. Replacing the battery by an ultracapacitor allows a faster recharge, with low maintenance costs, since ultracapacitors have a lifetime bigger than batteries; beyond reducing the environmental impact, as they don't use potentially toxic chemical compounds