Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneou... more Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneous illumination and temperature profiles which influence their performance. Under such conditions, the solar cell behavior is only accurately modeled if the diode and resistive losses are considered to be distributed across the solar cell instead of being gathered, as in the conventional lumped model. This paper presents a distributed diode model and its experimental validation, which was carried out for standard test conditions and a range of temperature and concentration levels going from 25 to 70 °C and 1 to 30 suns, respectively, for both homogeneous and a set of inhomogeneous profiles. Modeled and experimental results showed good agreement, thus validating the model. The results of traditional and distributed model approaches are compared with homogeneous and inhomogeneous profiles of irradiation and temperature. Finally, we analyze the effect of different profiles on cell performance.
This report review some of the most relevant aspects regarding thermal energy storage applied to ... more This report review some of the most relevant aspects regarding thermal energy storage applied to district energy & district heating systems. A general overview of the available technologies, as well as the past, present and future lines of work are presented with the respective literature. A methodology to assess the benefits of integrating a centralized short-term storage unit in a district energy model is described and implemented in modelica.
Modeling the Effects of Inhomogeneous Irradiation and Temperature Profile on CPV Solar Cell Behavior, 2015
Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneou... more Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneous illumination and temperature profiles which influence their performance. Under such conditions, the solar cell behavior is only accurately modeled if the diode and resistive losses are considered to be distributed across the solar cell instead of being gathered, as in the conventional lumped model. This paper presents a distributed diode model and its experimental validation, which was carried out for standard test conditions and a range of temperature and concentration levels going from 25 to 70 °C and 1 to 30 suns, respectively, for both homogeneous and a set of inhomogeneous profiles. Modeled and experimental results showed good agreement, thus validating the model. The results of traditional and distributed model approaches are compared with homogeneous and inhomogeneous profiles of irradiation and temperature. Finally, we analyze the effect of different profiles on cell performance.
In the context of meeting the targets set by 2050 for reducing greenhouse gas emissions, District... more In the context of meeting the targets set by 2050 for reducing greenhouse gas emissions, District Energy (DE) systems are considered to be a proven solution. This is essentially due to their ability to re-use energy that would otherwise be wasted, and its compatibility with a variety of other technologies, such as Thermal Energy Storage (TES) and renewable energy sources. When available, thermal energy storage provides greater flexibility, reliability, as well as energy security and it can be used to optimize equipment responsible for thermal energy production, as for instance, heat pumps. The main objective of this project is to study the influence of the introduction of short-term thermal storage in a DE, where heat and cold requirements are supplied by a combination of seasonal TES and heat pumps. To be specific, the focus is to analyze to what extent can short-term TES be used to shift the heat pumps electrical heating loads, from peak to off-peak periods, and quantify the influence of this strategy on energy production and electricity consumption. In order to do this, space heating and cooling demand data regarding a group of buildings is determined in Dymola/Modelica, and the energy systems performance is evaluated by using an analytical MATLAB model. The results obtained show that the introduction of short-term storage allowed to shift some of the thermal load from peak to off-peak periods. This operation led to a significant reduction in the individual electricity costs for the heat consumers (11.5% to 37.5%), which were determined based on electricity prices from the Dutch EPEX day-ahead spot market. Regarding electricity consumption and total heat production, it was noticed that the introduction of short-term storage led to an increase in the total heat output from heat pumps (~7%), mainly due to higher thermal losses. However, the global heat pumps coefficient of performance (COP) also increased (~14%), which resulted in less electricity consumption (~-13%), despite of the higher heat production.
As células solares fotovoltaicas (PV) que integram sistemas fotovoltaicos de concentração (CPV)
e... more As células solares fotovoltaicas (PV) que integram sistemas fotovoltaicos de concentração (CPV) estão sujeitas a grandes valores de irradiância, levando a densidades de corrente elevadas e a um possível sobreaquecimento. O aumento da temperatura de uma célula solar pode levar a uma redução da sua eficiência, tornando-se por vezes necessário utilizar métodos de arrefecimento nos sistemas CPV. Dependendo da configuração do sistema de arrefecimento, as células solares estão sujeitas a diferentes perfis de temperatura, os quais afectam a sua eficiência de forma diferente. O estudo da eficiência de uma célula solar quando sujeita a diferentes perfis de temperatura não homogéneos é abordado neste trabalho através de estudos computacionais e experimentais. Foi montado um setup experimental, que consiste num porta-amostras sobre o qual a célula será colocada, de modo a produzir diferentes perfis de temperatura, assim como distribuições de temperatura uniformes. A melhor configuração e os melhores materiais, de forma a produzir os padrões pretendidos, foram estudados através de simulações CFD-FEA (Computational Fluids Dynamics – Finite Element Analysis) usando SolidWorks. Foram aplicados vários padrões de temperatura ao porta-amostras. Após a sua caracterização, foram medidas curvas I-V para diferentes padrões de temperatura e assim analisado o efeito da nãouniformidade térmica em parâmetros eléctricos da célula. Os melhores resultados foram registados quando a célula foi submetida a menores temperaturas na zona da busbar. Os resultados obtidos serão também utilizados para validação do modelo do díodo distribuído, o qual foi desenvolvido para o estudo da influência de perfis não homogéneos de iluminação e temperatura em células CPV.
Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneou... more Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneous illumination and temperature profiles which influence their performance. Under such conditions, the solar cell behavior is only accurately modeled if the diode and resistive losses are considered to be distributed across the solar cell instead of being gathered, as in the conventional lumped model. This paper presents a distributed diode model and its experimental validation, which was carried out for standard test conditions and a range of temperature and concentration levels going from 25 to 70 °C and 1 to 30 suns, respectively, for both homogeneous and a set of inhomogeneous profiles. Modeled and experimental results showed good agreement, thus validating the model. The results of traditional and distributed model approaches are compared with homogeneous and inhomogeneous profiles of irradiation and temperature. Finally, we analyze the effect of different profiles on cell performance.
This report review some of the most relevant aspects regarding thermal energy storage applied to ... more This report review some of the most relevant aspects regarding thermal energy storage applied to district energy & district heating systems. A general overview of the available technologies, as well as the past, present and future lines of work are presented with the respective literature. A methodology to assess the benefits of integrating a centralized short-term storage unit in a district energy model is described and implemented in modelica.
Modeling the Effects of Inhomogeneous Irradiation and Temperature Profile on CPV Solar Cell Behavior, 2015
Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneou... more Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneous illumination and temperature profiles which influence their performance. Under such conditions, the solar cell behavior is only accurately modeled if the diode and resistive losses are considered to be distributed across the solar cell instead of being gathered, as in the conventional lumped model. This paper presents a distributed diode model and its experimental validation, which was carried out for standard test conditions and a range of temperature and concentration levels going from 25 to 70 °C and 1 to 30 suns, respectively, for both homogeneous and a set of inhomogeneous profiles. Modeled and experimental results showed good agreement, thus validating the model. The results of traditional and distributed model approaches are compared with homogeneous and inhomogeneous profiles of irradiation and temperature. Finally, we analyze the effect of different profiles on cell performance.
In the context of meeting the targets set by 2050 for reducing greenhouse gas emissions, District... more In the context of meeting the targets set by 2050 for reducing greenhouse gas emissions, District Energy (DE) systems are considered to be a proven solution. This is essentially due to their ability to re-use energy that would otherwise be wasted, and its compatibility with a variety of other technologies, such as Thermal Energy Storage (TES) and renewable energy sources. When available, thermal energy storage provides greater flexibility, reliability, as well as energy security and it can be used to optimize equipment responsible for thermal energy production, as for instance, heat pumps. The main objective of this project is to study the influence of the introduction of short-term thermal storage in a DE, where heat and cold requirements are supplied by a combination of seasonal TES and heat pumps. To be specific, the focus is to analyze to what extent can short-term TES be used to shift the heat pumps electrical heating loads, from peak to off-peak periods, and quantify the influence of this strategy on energy production and electricity consumption. In order to do this, space heating and cooling demand data regarding a group of buildings is determined in Dymola/Modelica, and the energy systems performance is evaluated by using an analytical MATLAB model. The results obtained show that the introduction of short-term storage allowed to shift some of the thermal load from peak to off-peak periods. This operation led to a significant reduction in the individual electricity costs for the heat consumers (11.5% to 37.5%), which were determined based on electricity prices from the Dutch EPEX day-ahead spot market. Regarding electricity consumption and total heat production, it was noticed that the introduction of short-term storage led to an increase in the total heat output from heat pumps (~7%), mainly due to higher thermal losses. However, the global heat pumps coefficient of performance (COP) also increased (~14%), which resulted in less electricity consumption (~-13%), despite of the higher heat production.
As células solares fotovoltaicas (PV) que integram sistemas fotovoltaicos de concentração (CPV)
e... more As células solares fotovoltaicas (PV) que integram sistemas fotovoltaicos de concentração (CPV) estão sujeitas a grandes valores de irradiância, levando a densidades de corrente elevadas e a um possível sobreaquecimento. O aumento da temperatura de uma célula solar pode levar a uma redução da sua eficiência, tornando-se por vezes necessário utilizar métodos de arrefecimento nos sistemas CPV. Dependendo da configuração do sistema de arrefecimento, as células solares estão sujeitas a diferentes perfis de temperatura, os quais afectam a sua eficiência de forma diferente. O estudo da eficiência de uma célula solar quando sujeita a diferentes perfis de temperatura não homogéneos é abordado neste trabalho através de estudos computacionais e experimentais. Foi montado um setup experimental, que consiste num porta-amostras sobre o qual a célula será colocada, de modo a produzir diferentes perfis de temperatura, assim como distribuições de temperatura uniformes. A melhor configuração e os melhores materiais, de forma a produzir os padrões pretendidos, foram estudados através de simulações CFD-FEA (Computational Fluids Dynamics – Finite Element Analysis) usando SolidWorks. Foram aplicados vários padrões de temperatura ao porta-amostras. Após a sua caracterização, foram medidas curvas I-V para diferentes padrões de temperatura e assim analisado o efeito da nãouniformidade térmica em parâmetros eléctricos da célula. Os melhores resultados foram registados quando a célula foi submetida a menores temperaturas na zona da busbar. Os resultados obtidos serão também utilizados para validação do modelo do díodo distribuído, o qual foi desenvolvido para o estudo da influência de perfis não homogéneos de iluminação e temperatura em células CPV.
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Papers by Fábio Batista
Projects by Fábio Batista
The main objective of this project is to study the influence of the introduction of short-term thermal storage in a DE, where heat and cold requirements are supplied by a combination of seasonal TES and heat pumps. To be specific, the focus is to analyze to what extent can short-term TES be used to shift the heat pumps electrical heating loads, from peak to off-peak periods, and quantify the influence of this strategy on energy production and electricity consumption.
In order to do this, space heating and cooling demand data regarding a group of buildings is determined in Dymola/Modelica, and the energy systems performance is evaluated by using an analytical MATLAB model. The results obtained show that the introduction of short-term storage allowed to shift some of the thermal load from peak to off-peak periods. This operation led to a significant reduction in the individual electricity costs for the heat consumers (11.5% to 37.5%), which were determined based on electricity prices from the Dutch EPEX day-ahead spot market. Regarding electricity consumption and total heat production, it was noticed that the introduction of short-term storage led to an increase in the total heat output from heat pumps (~7%), mainly due to higher thermal losses. However, the global heat pumps coefficient of performance (COP) also increased (~14%), which resulted in less electricity consumption (~-13%), despite of the higher heat production.
estão sujeitas a grandes valores de irradiância, levando a densidades de corrente elevadas e a um
possível sobreaquecimento. O aumento da temperatura de uma célula solar pode levar a uma redução
da sua eficiência, tornando-se por vezes necessário utilizar métodos de arrefecimento nos sistemas
CPV. Dependendo da configuração do sistema de arrefecimento, as células solares estão sujeitas a
diferentes perfis de temperatura, os quais afectam a sua eficiência de forma diferente.
O estudo da eficiência de uma célula solar quando sujeita a diferentes perfis de temperatura não
homogéneos é abordado neste trabalho através de estudos computacionais e experimentais. Foi
montado um setup experimental, que consiste num porta-amostras sobre o qual a célula será colocada,
de modo a produzir diferentes perfis de temperatura, assim como distribuições de temperatura
uniformes. A melhor configuração e os melhores materiais, de forma a produzir os padrões
pretendidos, foram estudados através de simulações CFD-FEA (Computational Fluids Dynamics –
Finite Element Analysis) usando SolidWorks.
Foram aplicados vários padrões de temperatura ao porta-amostras. Após a sua caracterização, foram
medidas curvas I-V para diferentes padrões de temperatura e assim analisado o efeito da nãouniformidade
térmica em parâmetros eléctricos da célula. Os melhores resultados foram registados
quando a célula foi submetida a menores temperaturas na zona da busbar. Os resultados obtidos serão
também utilizados para validação do modelo do díodo distribuído, o qual foi desenvolvido para o
estudo da influência de perfis não homogéneos de iluminação e temperatura em células CPV.
The main objective of this project is to study the influence of the introduction of short-term thermal storage in a DE, where heat and cold requirements are supplied by a combination of seasonal TES and heat pumps. To be specific, the focus is to analyze to what extent can short-term TES be used to shift the heat pumps electrical heating loads, from peak to off-peak periods, and quantify the influence of this strategy on energy production and electricity consumption.
In order to do this, space heating and cooling demand data regarding a group of buildings is determined in Dymola/Modelica, and the energy systems performance is evaluated by using an analytical MATLAB model. The results obtained show that the introduction of short-term storage allowed to shift some of the thermal load from peak to off-peak periods. This operation led to a significant reduction in the individual electricity costs for the heat consumers (11.5% to 37.5%), which were determined based on electricity prices from the Dutch EPEX day-ahead spot market. Regarding electricity consumption and total heat production, it was noticed that the introduction of short-term storage led to an increase in the total heat output from heat pumps (~7%), mainly due to higher thermal losses. However, the global heat pumps coefficient of performance (COP) also increased (~14%), which resulted in less electricity consumption (~-13%), despite of the higher heat production.
estão sujeitas a grandes valores de irradiância, levando a densidades de corrente elevadas e a um
possível sobreaquecimento. O aumento da temperatura de uma célula solar pode levar a uma redução
da sua eficiência, tornando-se por vezes necessário utilizar métodos de arrefecimento nos sistemas
CPV. Dependendo da configuração do sistema de arrefecimento, as células solares estão sujeitas a
diferentes perfis de temperatura, os quais afectam a sua eficiência de forma diferente.
O estudo da eficiência de uma célula solar quando sujeita a diferentes perfis de temperatura não
homogéneos é abordado neste trabalho através de estudos computacionais e experimentais. Foi
montado um setup experimental, que consiste num porta-amostras sobre o qual a célula será colocada,
de modo a produzir diferentes perfis de temperatura, assim como distribuições de temperatura
uniformes. A melhor configuração e os melhores materiais, de forma a produzir os padrões
pretendidos, foram estudados através de simulações CFD-FEA (Computational Fluids Dynamics –
Finite Element Analysis) usando SolidWorks.
Foram aplicados vários padrões de temperatura ao porta-amostras. Após a sua caracterização, foram
medidas curvas I-V para diferentes padrões de temperatura e assim analisado o efeito da nãouniformidade
térmica em parâmetros eléctricos da célula. Os melhores resultados foram registados
quando a célula foi submetida a menores temperaturas na zona da busbar. Os resultados obtidos serão
também utilizados para validação do modelo do díodo distribuído, o qual foi desenvolvido para o
estudo da influência de perfis não homogéneos de iluminação e temperatura em células CPV.