Simulation of Photovoltaic Panel Production as Complement to Ground Source Heat Pump System

This master thesis presents a new technological combination of two environmentally friendly sources of energy in order to provide DHW, and space heating. Solar energy is used for space heating, and DHW production using PV modules which supply direct current directly to electrical heating elements inside a water storage tank. On the other hand a GSHP system as another source of renewable energy provides heat in the water storage tank of the system in order to provide DHW and space heating. These two sources of renewable energy have been combined in this case-study in order to obtain a more efficient system, which will reduce the amount of electricity consumed by the GSHP system.The key aim of this study is to make simulations, and calculations of the amount ofelectrical energy that can be expected to be produced by a certain amount of PV modules that are already assembled on a house in Vantaa, southern Finland. This energy is then intended to be used as a complement to produce hot water in the heating system of the house beside the original GSHP system. Thus the amount of electrical energy purchased from the grid should be reduced and the compressor in the GSHP would need fewer starts which would reduce the heating cost of the GSHP system for space heating and providing hot water.The produced energy by the PV arrays in three different circuits will be charged directly to three electrical heating elements in the water storage tank of the existing system to satisfy the demand of the heating elements. The excess energy can be used to heat the water in the water storage tank to some extent which leads to a reduction of electricity consumption by the different components of the GSHP system.To increase the efficiency of the existing hybrid system, optimization of different PV configurations have been accomplished, and the results are compared. Optimization of the arrays in southern and western walls shows a DC power increase of 298 kWh/year compared with the existing PV configurations. Comparing the results from the optimization of the arrays on the western roof if the intention is to feed AC power to the components of the GSHP system shows a yearly AC power production of 1,646 kWh.This is with the consideration of no overproduction by the PV modules during the summer months. This means the optimized PV systems will be able to cover a larger part of summer demand compared with the existing system.

System Integration of PV/T Collectors in Solar Cooling Systems

The demand for cooling and air-conditioning of building is increasingly ever growing. This increase is mostly due to population and economic growth in developing countries, and also desire for a higher quality of thermal comfort. Increase in the use of conventional cooling systems results in larger carbon footprint and more greenhouse gases considering their higher electricity consumption, and it occasionally creates peaks in electricity demand from power supply grid. Solar energy as a renewable energy source is an alternative to drive the cooling machines since the cooling load is generally high when solar radiation is high. This thesis examines the performance of PV/T solar collector manufactured by Solarus company in a solar cooling system for an office building in Dubai, New Delhi, Los Angeles and Cape Town. The study is carried out by analyzing climate data and the requirements for thermal comfort in office buildings. Cooling systems strongly depend on weather conditions and local climate. Cooling load of buildings depend on many parameters such as ambient temperature, indoor comfort temperature, solar gain to the building and internal gains including; number of occupant and electrical devices. The simulations were carried out by selecting a suitable thermally driven chiller and modeling it with PV/T solar collector in Polysun software. Fractional primary energy saving and solar fraction were introduced as key figures of the project to evaluate the performance of cooling system. Several parametric studies and simulations were determined according to PV/T aperture area and hot water storage tank volume. The fractional primary energy saving analysis revealed that thermally driven chillers, particularly adsorption chillers are not suitable to be utilizing in small size of solar cooling systems in hot and tropic climates such as Dubai and New Delhi. Adsorption chillers require more thermal energy to meet the cooling load in hot and dry climates. The adsorption chillers operate in their full capacity and in higher coefficient of performance when they run in a moderate climate since they can properly reject the exhaust heat. The simulation results also indicated that PV/T solar collector have higher efficiency in warmer climates, however it requires a larger size of PV/T collectors to supply the thermally driven chillers for providing cooling in hot climates. Therefore using an electrical chiller as backup gives much better results in terms of primary energy savings, since PV/T electrical production also can be used for backup electrical chiller in a net metering mechanism.

Emissions from realistic operation of residential wood pellets heating systems

Emissions from residential combustion appliances vary significantly depending on the firing behaviours and combustion conditions, in addition to combustion technologies and fuel quality. Although wood pellet combustion in residential heating boilers is efficient, the combustion conditions during start-up and stop phases are not optimal and produce significantly high emissions such as carbon monoxide and hydrocarbon from incomplete combustion. The emissions from the start-up and stop phases of the pellet boilers are not fully taken into account in test methods for ecolabels which primarily focus on emissions during operation on full load and part load. The objective of the thesis is to investigate the emission characteristics during realistic operation of residential wood pellet boilers in order to identify when the major part of the annual emissions occur. Emissions from four residential wood pellet boilers were measured and characterized for three operating phases (start-up, steady and stop). Emissions from realistic operation of combined solar and wood pellet heating systems was continuously measured to investigate the influence of start-up and stop phases on total annual emissions. Measured emission data from the pellet devices were used to build an emission model to predict the annual emission factors from the dynamic operation of the heating system using the simulation software TRNSYS. Start-up emissions are found to vary with ignition type, supply of air and fuel, and time to complete the phase. Stop emissions are influenced by fan operation characteristics and the cleaning routine. Start-up and stop phases under realistic operation conditions contribute 80 – 95% of annual carbon monoxide (CO) emission, 60 – 90% total hydrocarbon (TOC), 10 – 20% of nitrogen oxides (NO), and 30 – 40% particles emissions. Annual emission factors from realistic operation of tested residential heating system with a top fed wood pelt boiler can be between 190 and 400 mg/MJ for the CO emissions, between 60 and 95 mg/MJ for the NO, between 6 and 25 mg/MJ for the TOC, between 30 and 116 mg/MJ for the particulate matter and between 2x10-13 /MJ and 4x10-13 /MJ for the number of particles. If the boiler has the cleaning sequence with compressed air such as in boiler B2, annual CO emission factor can be up to 550 mg/MJ. Average CO, TOC and particles emissions under realistic annual condition were greater than the limits values of two eco labels. These results highlight the importance of start-up and stop phases in annual emission factors (especially CO and TOC). Since a large or dominating part of the annual emissions in real operation arise from the start-up and stop sequences, test methods required by the ecolabels should take these emissions into account. In this way it will encourage the boiler manufacturers to minimize annual emissions. The annual emissions of residential pellet heating system can be reduced by optimizing the number of start-ups of the pellet boiler. It is possible to reduce up to 85% of the number of start-ups by optimizing the system design and its controller such as switching of the boiler pump after it stops, using two temperature sensors for boiler ON/OFF control, optimizing of the positions of the connections to the storage tank, increasing the mixing valve temperature in the boiler circuit and decreasing the pump flow rate. For 85 % reduction of start-ups, 75 % of CO and TOC emission factors were reduced while 13% increase in NO and 15 % increase in particle emissions was observed.

Desenvolvimento de um programa de simulação computacional de sistemas de aquecimento solar para água

Esta Tese apresenta uma análise do comportamento térmico de um sistema de aquecimento solar operando por termossifão. Neste tipo de sistema o fluido no coletor solar é circulado por convecção natural, que acontece devido à diferença de massa específica da água ao longo circuito. Nestes sistemas a vazão mássica varia ao longo do dia e do ano, dependendo, dentre outros fatores, da irradiância solar absorvida, do perfil de temperaturas da água no sistema, da geometria, do volume e do perfil de demanda de água quente. Para uma avaliação detalhada do comportamento térmico de aquecedores solares operando por termossifão foram realizados ensaios experimentais e cálculos teóricos. Os resultados dos experimentos concordaram com aqueles apresentados na literatura e sua análise fundamentou o desenvolvimento do aplicativo TermoSim, um programa de simulação computacional do comportamento térmico de sistemas de aquecimento de água com energia solar. O tratamento matemático adotado no TermoSim compreende a modelagem dos coletores solares de acordo com a teoria de Hottel-Bliss-Whillier. O reservatório térmico é modelado com estratificação térmica, convecção e condução entre as camadas. A vazão mássica é obtida a partir do balanço da quantidade de movimento no circuito. Os modelos matemáticos empregados na construção do aplicativo TermoSim foram validados através do confronto dos resultados simulados com medidas experimentais. Foi demonstrado que a utilização destes modelos é adequada e permite reproduzir com precisão o comportamento térmico dos coletores solares e do reservatório térmico. Além do programa TermoSim, foi também desenvolvido o programa TermoDim, que é uma ferramenta para o dimensionamento de sistemas de aquecimento solar, que requer apenas o conhecimento dos parâmetros geométricos do sistema, dados meteorológicos em média mensal e informação a respeito do volume de demanda. O TermoDim é apropriado para estimar o desempenho de aquecedores solares operando por termossifão com tanques verticais e horizontais. O método de dimensionamento do TermoDim é baseado na correlação para a eficiência média mensal obtida neste trabalho a partir de um grande número de simulações.

Projeto, construção e análise de desempenho de coletores solares alternativos utilizando garrafas pet

A solar alternative system for water heating is presented. It work on a thermosiphon, consisting of one or two alternative collectors and a water storage tank also alternative, whose main purpose is to socialize the use of energy mainly to be used by people of low income. The collectors were built from the use of pets bottles, cans of beer and soft drinks and tubes of PVC, ½ " and the thermal reservoirs from a drum of polyethylene used for storage of water and garbage placed inside cylinder of fiber glass and EPS ground between the two surfaces. Such collectors are formed by three elements: pet bottles, cans and tubes absorbers. The heating units, which form the collector contains inside the cans that can be closed, in original form or in the form of plate. The collectors have an absorber grid formed by eight absorbers PVC tube, connected through connections at T of the same material and diameter. It will be presented data of the thermal parameters which demonstrate the efficiency of the heating system proposed. Relative aspects will be boarded also the susceptibility the thermal degradation and for UV for the PVC tubes. It will be demonstrated that this alternative heating system, which has as its main feature low cost, presents thermal, economic and materials viabilities

Influência da intensidade de aeração na formação do floco de lodo ativado e na eficiência de remoção de matéria orgânica

In wastewater treatment, activated sludge systems have been a technology widely applied as secondary treatment. During this step, which has a strong biological aspect, it is necessary to introduce oxygen supply for the maintenance of metabolic activity of the bacteria through the aerators. Aeration devices are responsible for most of the energy consumption in this stage. In this background, the influence of three aeration intensities (atmospheric air flow 3.5, 7.0 and 10.5 L.min-1) and the concentration of dissolved oxygen (DO) on the dimension of activated sludge flocs as well as on the efficiency of organic matter removal were assessed using a traditional activated sludge system which was fed with synthetic domestic wastewater. Samples were taken weekly from the three units that make up the system feed, aeration and storage tank in order to verify the Chemical Oxygen Demand (COD). It was established the process efficiency through a comparison between the initial and final COD. Besides the parameters already mentioned, this monitoring work on activated sludge batch system was also observed by Mixed Liquor Suspend Solids (MLSS), Volatile Suspend Solids (VSS), pH and temperature measures. The results have showed a maximum removal efficiency around 75% in the first aeration sequence and approximately 85% for the second and third one. For the first aeration, the DO concentration remained higher than 3.0 mg.L-1 and a diameter range from 10 to 60 μm was observed. In the second e third sequence, the DO concentration remained higher than 4.0 mg.L-1 with a diameter range of 10 until 200 μm. Although the sequence 1 and 2 have presented similar performances for organic matter removal, the sequence 2 promoted a regular floc size distribution and with lower values of Sludge Volumetric Index (SVI) meaning a better flocculating ability. In addition, the results reaffirmed what the literature has reported: higher DO concentrations produce flocs with greater dimensions

Laboratory study on the bioremediation of diesel oil contaminated soil from a petrol station

O objetivo do presente estudo foi investigar possíveis métodos para aumentar a taxa de biodegradação aeróbia de hidrocarbonetos (tratamentos ex-situ). Neste trabalho, processos de biorremediação foram aplicados a um solo arenoso com alto nível de contaminação ocasionada por um vazamento de um tanque de armazenamento de óleo diesel subterrâneo em um posto de combustíveis. Experimentos em escala laboratorial (respirômetros de Bartha) foram utilizados para avaliar a biodegradação do óleo diesel. Estímulo da biodegradação foi realizado utilizando-se as técnicas de bioestímulo (adição de soluções de nitrogênio e fósforo ou surfactante Tween 80) e de bioaumento (consórcio bacteriano isolado de um sistema de landfarming). Para investigar as interações entre os fatores otimizadores, e encontrar a melhor combinação entre esses agentes, o estudo foi baseado em um delineamento experimental fatorial completo. A eficiência de biodegradação foi simultaneamente medida com dois métodos: respirométrico (produção de CO2 microbiano) e cromatografia gasosa. Testes de toxicidade aguda com Daphnia similis foram aplicados para examinar a eficiência dos processos em termos de geração de produtos menos tóxicos. Resultados mostraram que todas as estratégias de biorremediação aceleraram a biorremediação natural do solo contaminado e os melhores resultados foram obtidos quando os tratamentos tinham adição de nutrientes. Dados respirométricos indicaram uma máxima mineralização de hidrocarbonetos de 19,8%, obtida com a combinação dos três agentes, com uma remoção de hidrocarbonetos totais de petróleo (TPH) de 45,5% em 55 dias de tratamento. No final dos experimentos, duas espécies predominantes de bactéria foram isoladas e identificadas como Staphylococcus hominis e Kocuria palustris.

Monitoramento sanitário de um sistema integrado de tratamento de águas residuárias da suinocultura

Objective. To assess the potential for contamination of wastewaters from pig farming. Methods. Wastewaters from pig farming were stored in a tank. After 0, 30, 60, 90, and 120 days of hydraulic retention, they were added to lysimeters filled with argillaceous, sandy, or medium soil. Finally, these lysimeters were submitted to simulations of either a rainy season or a dry season. The number of colony-forming units (CFUs) of total coliforms, fecal coliforms, and fecal streptococci was measured in the effluents of the storage tank (for the various periods of hydraulic retention), in the percolate from the lysimeters, and in the three types of soil. The microbiological analyses were carried out using the membrane filter technique. The pH analyses were done potentiometrically. Results. For the three microorganisms, the largest decrease in bacterial counts in the storage tanks occurred with 90 or 120 days of retention. There was a marked decrease in the bacterial count in the percolates of the three soils. For the three soil types the greatest reduction in bacterial counts was found in medium soil, due to its acidity (pH < 7.0). Hydraulic retention was not sufficient to ensure the sanitary adequacy of the wastewaters and their use for irrigation, given that fecal coliform values were above 1 000 CFU per 100 mL. Therefore, adding the residues to the soil was considered a second stage of treatment. Conclusions. The retention of wastewaters followed by adding them to soil was effective in minimizing the contaminating effect of pig farming residues. The storage time for wastewaters from pig farming could be decreased from 120 to 90 days.

Coeficiente de operación de un sistema formado por un refrigerador doméstico acoplado a un acumulador de agua caliente para la recuperación de energía

An experimental apparatus containing a domestic refrigerator coupled to a vertical hot water storage tank was used for energy recovery. The original condenser of the refrigerator was maintained, but modified with a concentric tubes heat exchanger with countercurrent water and refrigerating gas flows. The coefficient of performance for the heat pump is calculated by the ratio of energy in the heat storage and the electric power consumed by the domestic refrigerator compressor. The results show that the increasing of hydrostatic pressure in the storage tank increases the water flow rate and the coefficient of performance. The proposed device also reduces the heat dissipation to the surroundings. This is more important in small confinements found in low-cost houses.

Aplicação da técnica de elementos finitos na estratificação de armazenadores térmicos com barreiras de meios porosos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modelo matemático para análise de problemas de estocagem de líquidos que apresentam estratificação térmica

Pós-graduação em Engenharia Mecânica - FEB

Análise numérica de um coletor solar de tubo evacuado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Levantamento de coeficientes de desempenho de armazenador térmico associado a refrigerador doméstico modificado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise numérica da convecção natural em dispositivos solar integrados coletor-tanque

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização geológico-geotécnica aplicada à instalação de postos de combustíveis em Rio Claro (SP)

Pós-graduação em Geociências e Meio Ambiente - IGCE