This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existi... more This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existing, validated detailed model was used to identify the formula’s coefficients by comparing the simulation results of both models. The accuracy of the simplified model as well as the influence of the set of simulations used to establish the model has been investigated. The simplified model has been compared to other formulas. The model has proven to be able to predict accurately the collector efficiency.
Innovative building-integrated components provide solar heating, solar control and visual contact... more Innovative building-integrated components provide solar heating, solar control and visual contact to the exterior. However, their contributions to the building are challenging to predict. This paper presents the results of a detailed physical model which show that the g value depends not only on the position of the sun, but also on the collector operation mode. For successful marketing of such innovative components, a new standard would be helpful which clarifies when a detailed model can be considered to be validated by measurements. Customers could then check different applications with easy-to-use models. Keywords: variable g value, transparent solar thermal collector (TSTC), building-integrated solar thermal systems (BIST), TRNSYS
This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existi... more This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existing, validated detailed model was used to identify the formula’s coefficients by comparing the simulation results of both models. The accuracy of the simplified model as well as the influence of the set of simulations used to establish the model has been investigated. The simplified model has been compared to other formulas. The model has proven to be able to predict accurately the collector efficiency.
Transparent solar thermal collectors (TSTC) as presented by Figure 1 indicate primary energy savi... more Transparent solar thermal collectors (TSTC) as presented by Figure 1 indicate primary energy savings – even in comparison with an opaque wall [1, 2]. Figure 1 Schematic drawing of a TSTC. An absorber with openings and slats is mounted inside of three glass panes. [2] While conventional collector measurements focus on predicting the collector gain, TSTC need to quantify the heat flux into the building and the solar transmission, too. This paper presents the measurement equipment as well as the modelling based on the measurement results. A detailed physical model of TSTC [3] offers predictions of the benefits, easy collector optimizations and more, but also the possibility of quantifying the uncertainties of the simulation. The method to determine these uncertainties is presented in the last subsection.
1. Einführung Bei der Integration von Fassadenkollektoren in den Sichtbereich des Innenraums spie... more 1. Einführung Bei der Integration von Fassadenkollektoren in den Sichtbereich des Innenraums spielen nicht nur energetische Aspekte, sondern auch der visuelle Komfort eine Rolle. Dabei ist darauf zu achten, dass sowohl eine Durchsicht nach draußen als auch ein Blendschutz gewährleistet ist. Eine Röhre eines fassadenintegrierten Vakuumröhrenkollektors bildet vom Innenraum aus betrachtet bei Bestrahlung zwei vom Auge wahrnehmbare helle Örtlichkeiten an den Mantelrändern der Glasröhre. Abbildung 1 veranschaulicht diese hellen Orte. Die Strahlung fällt dabei orthogonal zur Röhrenachse ein. Abbildung 1: Helle Örtlichkeiten an den Mantelrändern einer Glasröhre unter Bestrahlung
Within the European research project RETROKIT (http://www.retrokitproject.eu) and supported by a ... more Within the European research project RETROKIT (http://www.retrokitproject.eu) and supported by a partner network all over Europe, a low-cost building-integrated photovoltaic thermal (BIPVT) component was developed. This component is part of a prefabricated façade that can be easily retrofitted on old residential buildings with little or no energy efficiency infrastructure. The innovation of this project lies in two basic aspects. First of all, it is customizable and can be installed and maintained easily, making the refurbishing process more simple and systematic. Additionally, due to the component's low cost it is accessible for residential owners who represent a high potential market. This RETROKIT facade consists of different layers. The first layer, at the front surface of the module is the PV element of the collector and is constructed with the CIGS thin film PV technology. Behind the PV component, there are capillary tubes to remove the solar thermal energy. And at the bac...
Luftkollektoren weisen gegenüber flüssigkeitsdurchströmten Kollektoren mehrere signifikante Vorte... more Luftkollektoren weisen gegenüber flüssigkeitsdurchströmten Kollektoren mehrere signifikante Vorteile auf, und es laufen Aktivitäten zur Verbesserung der Rahmenbedingungen. Daher wurde am Fraunhofer ISE das EU-geförderte Projekt Cost-Effective (Förderkennzeichen: NMP2-LA-2008-212206) bearbeitet, und derzeit werden das BMU-geförderte Projekt Luko-E (Förderkennzeichen: 0325959A) sowie darüber hinausgehende Untersuchungen durchgeführt. Bisher wurden die stark massenstromabhängigen Mess- oder Simulationsergebnisse von Luftkollektoren für einzelne Massenströme dargestellt, womit sie schwer vergleichbar waren. In dieser Arbeit werden Methoden beschrieben, den Systembezug unter Berücksichtigung des Druckverlusts herzustellen, um die Vergleichbarkeit zu verbessern. Zunächst werden Systeme und Luftkollektoren über ihren nicht massenstromabhängigen Strömungswiderstand als hydraulischen Kennwert definiert bzw. charakterisiert. Abbildung 1: Differenz aus thermischer Leistung des Luftkollektors u...
ABSTRACT To prevent the overheating of a well-insulated building in summer, facade elements with ... more ABSTRACT To prevent the overheating of a well-insulated building in summer, facade elements with switchable U-value are a possible solution. A new translucent element with switchable U-value is presented. The convection around a translucent insulation panel is controlled by moving this panel vertically within the double glazing unit. Measurements of such elements show a possible switching of more than +100% of the U-value between the insulating and conducting state. Various geometries have been measured, and the influence of CO2 in the cavity has also been investigated. Based on the experimental results, TRNSYS simulations have been performed to investigate the overall performance of such a new element integrated in a real building. An optimized element could lead to a reduction of the cooling demand of up to 29.6% of the useful energy and to large improvements in the summer comfort.
This report presents a current overview of available technologies for facade-integrated solar the... more This report presents a current overview of available technologies for facade-integrated solar thermal systems. First, glazings are anaylised, followed by available absorber technologies. Then, available collectors and systems are presented, fluid-based ones as well as with air as heat transfer medium, vacuum tubes as well as semitransparent collectors.
This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existi... more This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existing, validated detailed model was used to identify the formula’s coefficients by comparing the simulation results of both models. The accuracy of the simplified model as well as the influence of the set of simulations used to establish the model has been investigated. The simplified model has been compared to other formulas. The model has proven to be able to predict accurately the collector efficiency.
Innovative building-integrated components provide solar heating, solar control and visual contact... more Innovative building-integrated components provide solar heating, solar control and visual contact to the exterior. However, their contributions to the building are challenging to predict. This paper presents the results of a detailed physical model which show that the g value depends not only on the position of the sun, but also on the collector operation mode. For successful marketing of such innovative components, a new standard would be helpful which clarifies when a detailed model can be considered to be validated by measurements. Customers could then check different applications with easy-to-use models. Keywords: variable g value, transparent solar thermal collector (TSTC), building-integrated solar thermal systems (BIST), TRNSYS
This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existi... more This paper presents a simplified model for Transparent Solar Thermal Collectors (TSTC). An existing, validated detailed model was used to identify the formula’s coefficients by comparing the simulation results of both models. The accuracy of the simplified model as well as the influence of the set of simulations used to establish the model has been investigated. The simplified model has been compared to other formulas. The model has proven to be able to predict accurately the collector efficiency.
Transparent solar thermal collectors (TSTC) as presented by Figure 1 indicate primary energy savi... more Transparent solar thermal collectors (TSTC) as presented by Figure 1 indicate primary energy savings – even in comparison with an opaque wall [1, 2]. Figure 1 Schematic drawing of a TSTC. An absorber with openings and slats is mounted inside of three glass panes. [2] While conventional collector measurements focus on predicting the collector gain, TSTC need to quantify the heat flux into the building and the solar transmission, too. This paper presents the measurement equipment as well as the modelling based on the measurement results. A detailed physical model of TSTC [3] offers predictions of the benefits, easy collector optimizations and more, but also the possibility of quantifying the uncertainties of the simulation. The method to determine these uncertainties is presented in the last subsection.
1. Einführung Bei der Integration von Fassadenkollektoren in den Sichtbereich des Innenraums spie... more 1. Einführung Bei der Integration von Fassadenkollektoren in den Sichtbereich des Innenraums spielen nicht nur energetische Aspekte, sondern auch der visuelle Komfort eine Rolle. Dabei ist darauf zu achten, dass sowohl eine Durchsicht nach draußen als auch ein Blendschutz gewährleistet ist. Eine Röhre eines fassadenintegrierten Vakuumröhrenkollektors bildet vom Innenraum aus betrachtet bei Bestrahlung zwei vom Auge wahrnehmbare helle Örtlichkeiten an den Mantelrändern der Glasröhre. Abbildung 1 veranschaulicht diese hellen Orte. Die Strahlung fällt dabei orthogonal zur Röhrenachse ein. Abbildung 1: Helle Örtlichkeiten an den Mantelrändern einer Glasröhre unter Bestrahlung
Within the European research project RETROKIT (http://www.retrokitproject.eu) and supported by a ... more Within the European research project RETROKIT (http://www.retrokitproject.eu) and supported by a partner network all over Europe, a low-cost building-integrated photovoltaic thermal (BIPVT) component was developed. This component is part of a prefabricated façade that can be easily retrofitted on old residential buildings with little or no energy efficiency infrastructure. The innovation of this project lies in two basic aspects. First of all, it is customizable and can be installed and maintained easily, making the refurbishing process more simple and systematic. Additionally, due to the component's low cost it is accessible for residential owners who represent a high potential market. This RETROKIT facade consists of different layers. The first layer, at the front surface of the module is the PV element of the collector and is constructed with the CIGS thin film PV technology. Behind the PV component, there are capillary tubes to remove the solar thermal energy. And at the bac...
Luftkollektoren weisen gegenüber flüssigkeitsdurchströmten Kollektoren mehrere signifikante Vorte... more Luftkollektoren weisen gegenüber flüssigkeitsdurchströmten Kollektoren mehrere signifikante Vorteile auf, und es laufen Aktivitäten zur Verbesserung der Rahmenbedingungen. Daher wurde am Fraunhofer ISE das EU-geförderte Projekt Cost-Effective (Förderkennzeichen: NMP2-LA-2008-212206) bearbeitet, und derzeit werden das BMU-geförderte Projekt Luko-E (Förderkennzeichen: 0325959A) sowie darüber hinausgehende Untersuchungen durchgeführt. Bisher wurden die stark massenstromabhängigen Mess- oder Simulationsergebnisse von Luftkollektoren für einzelne Massenströme dargestellt, womit sie schwer vergleichbar waren. In dieser Arbeit werden Methoden beschrieben, den Systembezug unter Berücksichtigung des Druckverlusts herzustellen, um die Vergleichbarkeit zu verbessern. Zunächst werden Systeme und Luftkollektoren über ihren nicht massenstromabhängigen Strömungswiderstand als hydraulischen Kennwert definiert bzw. charakterisiert. Abbildung 1: Differenz aus thermischer Leistung des Luftkollektors u...
ABSTRACT To prevent the overheating of a well-insulated building in summer, facade elements with ... more ABSTRACT To prevent the overheating of a well-insulated building in summer, facade elements with switchable U-value are a possible solution. A new translucent element with switchable U-value is presented. The convection around a translucent insulation panel is controlled by moving this panel vertically within the double glazing unit. Measurements of such elements show a possible switching of more than +100% of the U-value between the insulating and conducting state. Various geometries have been measured, and the influence of CO2 in the cavity has also been investigated. Based on the experimental results, TRNSYS simulations have been performed to investigate the overall performance of such a new element integrated in a real building. An optimized element could lead to a reduction of the cooling demand of up to 29.6% of the useful energy and to large improvements in the summer comfort.
This report presents a current overview of available technologies for facade-integrated solar the... more This report presents a current overview of available technologies for facade-integrated solar thermal systems. First, glazings are anaylised, followed by available absorber technologies. Then, available collectors and systems are presented, fluid-based ones as well as with air as heat transfer medium, vacuum tubes as well as semitransparent collectors.
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Papers by Christoph Maurer