Final Report Summary - PV/T/D (Multifunctional PV/Thermal/Daylighting Roof Panels for Atrium Buildings and Large Green Houses)
1) A summary description of the project objectives
The aim of this fellowship project is to investigate a novel multifunctional PV/Thermal/Daylighting (PV/T/D) roof panel for atrium buildings and large greenhouses. The panel has a structure containing miniature dielectric CPCs (Compound Parabolic Concentrators) to provide concentration of the solar radiation coming from a certain range of sky angles and meanwhile allow the remaining solar radiation to transmit for daylighting. As a result, the panel will also provide a solar shading function and an option to incorporate concentration PV for PV/Thermal applications. The principle of perforated plate heat recovery will be employed to remove heat rejection from PV and reduce heat gain to the atrium (or greenhouse) space.
2) A description of the work performed since the beginning of the project
The research activities of the project have been well carried out since the beginning of the project. The specific objectives of the project and the corresponding implementations are presented below:
• Ray-tracing simulation of dielectric CPC panels for daylighting control
Ray-tracing simulation of the miniature CPC (Compound Parabolic Concentrator) panels has been carried out to optimize its geometry for the combined function of daylighting and solar concentration which is also the solar shading for an atrium (or greenhouse) space. A comparison with the conventional prismatic elements has been made to show the advantage of a dielectric CPC for daylighting control. Simulation has also been made to investigate different design considerations in order to join the miniature dielectric CPCs to form a dielectric CPC panel. The optical concentration ratio and daylight transmittance of the dielectric CPC panel have been given in simulation for different sky conditions in various typical geographic locations.
• Fabrication and experiment of the key component dielectric CPC panels
The key component miniature CPC rods and panels have been fabricated using CNC (computer numerical control) machining, and the samples have been tested under both solar simulator and real sky conditions. An experimental comparison of a miniature CPC rod with the conventional prismatic elements has shown the advantage of a dielectric CPC for daylighting control in terms of transmittance changing with time.
• Computer Fluid Dynamics (CFD) modeling
Computerized Fluid Dynamic (CFD) modeling has been carried out to investigate the characteristics of air flow through the perforated glazing and within the channel between the perforated glazing and the dielectric CPC panel, and hence to determine heat transfer in the proposed PV/Thermal/Daylighting (PV/T/D) panel. The simulation results show the distribution of temperatures, heat flux and air velocities, and hence the heat recovery efficiency has been calculated. The results show that use of a perforated glazing can largely reduce solar heat gain to an atrium (or green house) space.
• Construction, testing and monitoring of a model atrium with installation of a prototype PV/T/D panel;
A small-scale prototype PV/T/D panel has been constructed. An indoor experiment has been conducted first to study the heat transfer characteristics in the channel between a dielectric CPC panel and a perforated glazing. The heat recovery efficiency has been determined from the measured parameters. An outdoor experiment has been carried out to investigate the function of the PV/T/D panel for combined PV/Thermal and daylighting. The expected results have been obtained in the experiments.
• Economic and environmental benefits
The potential economic and environmental benefits of the proposed PV/T/D roof panel have been analysed. The payback period of a PV/T/D roof panel has been estimated for some selected locations.
• Dissemination and exploitation
The novel design concept of the multifunctional PV/Thermal/Daylighting roof panel based on use of dielectric CPC has been presented at several conferences and seminars. The research activities of this project have also generated a number of research articles. A patent application has also been prepared to protect the technological concept and details of the structure design.
3) A description of the main results achieved so far
The main results achieved so far are listed as follows and also shown in attached figures:
• Ray-tracing simulation of the dielectric CPC panel has been carried out to optimize its geometry for the combined function of daylighting and solar concentration which also serves as the solar shading for an atrium (or greenhouse) space. The results have been obtained on comparison of dielectric CPC with common prismatic structures for both different incidence angles and standard sky conditions.
• The key component miniature CPC rods and panels have been fabricated using CNC (computer numerical control) machining, and the samples have been tested under both solar simulator and real sky conditions.
• Computer Fluid Dynamics (CFD) modeling of air flow through the channel below a dielectric CPC panel has been conducted to determine the heat recovery performance and potential optimum design parameters for the perforated glazing sheet to be adopted in the design of a PV/Thermal/Daylighting panel.
• A small-scale prototype PV/Thermal/Daylighting panel has been constructed and tested.
• The potential economic and environmental benefits of the proposed PV/T/D roof panel have been analysed. The results show that use of a PV/T/D roof panel is of more benefit for the locations with a longer air-conditioning period.
• 3 conference presentations about the project have been made and 3 research papers have been submitted to international journals. In addition, Marie Curie Actions has been also acknowledged in 3 published journal papers and other 6 submitted journal papers jointly written by the incoming fellow and the host researcher.
4) The expected final results and their potential impact and use
This project is expected to provide a novel multifunctional PV/Thermal/Daylighting (PV/T/D) roof panel for atrium buildings and large greenhouses. The fundamental research has been carried out and a small-scale prototype system has been constructed and tested through this fellowship project. The testing results are promising and will be continuously disseminated widely to attract potential commercial interest. Development of low/zero carbon emission buildings using renewable energy sources is the fundamental approach to meet the EU target in cutting CO2 emissions. The proposed multifunctional PV/T/D roof panels are suitable for atrium buildings and large greenhouses as well, so they may play an important role in promoting solar energy applications in buildings to make a significant contribution to the EU target in cutting CO2 emissions, and hence the quality of life both within the EU and globally would be improved. Results would be of great value to industries of building-integrated PV, daylighting and glazing. The proposed technology has the potential to find a large market both in the EU and worldwide, and would therefore bring economic benefit to EU industry. Manufacturing and application of the proposed technology would also create new job opportunities in the EU.
The aim of this fellowship project is to investigate a novel multifunctional PV/Thermal/Daylighting (PV/T/D) roof panel for atrium buildings and large greenhouses. The panel has a structure containing miniature dielectric CPCs (Compound Parabolic Concentrators) to provide concentration of the solar radiation coming from a certain range of sky angles and meanwhile allow the remaining solar radiation to transmit for daylighting. As a result, the panel will also provide a solar shading function and an option to incorporate concentration PV for PV/Thermal applications. The principle of perforated plate heat recovery will be employed to remove heat rejection from PV and reduce heat gain to the atrium (or greenhouse) space.
2) A description of the work performed since the beginning of the project
The research activities of the project have been well carried out since the beginning of the project. The specific objectives of the project and the corresponding implementations are presented below:
• Ray-tracing simulation of dielectric CPC panels for daylighting control
Ray-tracing simulation of the miniature CPC (Compound Parabolic Concentrator) panels has been carried out to optimize its geometry for the combined function of daylighting and solar concentration which is also the solar shading for an atrium (or greenhouse) space. A comparison with the conventional prismatic elements has been made to show the advantage of a dielectric CPC for daylighting control. Simulation has also been made to investigate different design considerations in order to join the miniature dielectric CPCs to form a dielectric CPC panel. The optical concentration ratio and daylight transmittance of the dielectric CPC panel have been given in simulation for different sky conditions in various typical geographic locations.
• Fabrication and experiment of the key component dielectric CPC panels
The key component miniature CPC rods and panels have been fabricated using CNC (computer numerical control) machining, and the samples have been tested under both solar simulator and real sky conditions. An experimental comparison of a miniature CPC rod with the conventional prismatic elements has shown the advantage of a dielectric CPC for daylighting control in terms of transmittance changing with time.
• Computer Fluid Dynamics (CFD) modeling
Computerized Fluid Dynamic (CFD) modeling has been carried out to investigate the characteristics of air flow through the perforated glazing and within the channel between the perforated glazing and the dielectric CPC panel, and hence to determine heat transfer in the proposed PV/Thermal/Daylighting (PV/T/D) panel. The simulation results show the distribution of temperatures, heat flux and air velocities, and hence the heat recovery efficiency has been calculated. The results show that use of a perforated glazing can largely reduce solar heat gain to an atrium (or green house) space.
• Construction, testing and monitoring of a model atrium with installation of a prototype PV/T/D panel;
A small-scale prototype PV/T/D panel has been constructed. An indoor experiment has been conducted first to study the heat transfer characteristics in the channel between a dielectric CPC panel and a perforated glazing. The heat recovery efficiency has been determined from the measured parameters. An outdoor experiment has been carried out to investigate the function of the PV/T/D panel for combined PV/Thermal and daylighting. The expected results have been obtained in the experiments.
• Economic and environmental benefits
The potential economic and environmental benefits of the proposed PV/T/D roof panel have been analysed. The payback period of a PV/T/D roof panel has been estimated for some selected locations.
• Dissemination and exploitation
The novel design concept of the multifunctional PV/Thermal/Daylighting roof panel based on use of dielectric CPC has been presented at several conferences and seminars. The research activities of this project have also generated a number of research articles. A patent application has also been prepared to protect the technological concept and details of the structure design.
3) A description of the main results achieved so far
The main results achieved so far are listed as follows and also shown in attached figures:
• Ray-tracing simulation of the dielectric CPC panel has been carried out to optimize its geometry for the combined function of daylighting and solar concentration which also serves as the solar shading for an atrium (or greenhouse) space. The results have been obtained on comparison of dielectric CPC with common prismatic structures for both different incidence angles and standard sky conditions.
• The key component miniature CPC rods and panels have been fabricated using CNC (computer numerical control) machining, and the samples have been tested under both solar simulator and real sky conditions.
• Computer Fluid Dynamics (CFD) modeling of air flow through the channel below a dielectric CPC panel has been conducted to determine the heat recovery performance and potential optimum design parameters for the perforated glazing sheet to be adopted in the design of a PV/Thermal/Daylighting panel.
• A small-scale prototype PV/Thermal/Daylighting panel has been constructed and tested.
• The potential economic and environmental benefits of the proposed PV/T/D roof panel have been analysed. The results show that use of a PV/T/D roof panel is of more benefit for the locations with a longer air-conditioning period.
• 3 conference presentations about the project have been made and 3 research papers have been submitted to international journals. In addition, Marie Curie Actions has been also acknowledged in 3 published journal papers and other 6 submitted journal papers jointly written by the incoming fellow and the host researcher.
4) The expected final results and their potential impact and use
This project is expected to provide a novel multifunctional PV/Thermal/Daylighting (PV/T/D) roof panel for atrium buildings and large greenhouses. The fundamental research has been carried out and a small-scale prototype system has been constructed and tested through this fellowship project. The testing results are promising and will be continuously disseminated widely to attract potential commercial interest. Development of low/zero carbon emission buildings using renewable energy sources is the fundamental approach to meet the EU target in cutting CO2 emissions. The proposed multifunctional PV/T/D roof panels are suitable for atrium buildings and large greenhouses as well, so they may play an important role in promoting solar energy applications in buildings to make a significant contribution to the EU target in cutting CO2 emissions, and hence the quality of life both within the EU and globally would be improved. Results would be of great value to industries of building-integrated PV, daylighting and glazing. The proposed technology has the potential to find a large market both in the EU and worldwide, and would therefore bring economic benefit to EU industry. Manufacturing and application of the proposed technology would also create new job opportunities in the EU.
