ABSTRACT This paper presents component performance results of a new parabolic trough collector ar... more ABSTRACT This paper presents component performance results of a new parabolic trough collector array driving an organic Rankine cycle (ORC) power generation system. The system has been installed in the National Solar Energy Centre at CSIRO Energy Technology in Newcastle, NSW, Australia. It consists of four rows of 18 parabolic mirrors each in a 2×2 matrix with a total aperture area of approximately 132m2 . The absorber tube is a laterally aligned, 40mm copper tube coated with a semi-selective paint and enclosed in a 50mm non-evacuated glass tube to reduce convection losses. The mirror modules, which are light-weight and robust, are made from thin low iron back silvered glass bonded to a sheet steel substrate. They are supported by a box truss on semi circular hoops running on rollers for single axis tracking. The mirror design has been chosen to allow low-cost manufacturing as well as simple commissioning and operation. The ORC unit is a FP6 unit sourced from Freepower Ltd. with a net power output of 6kWel at 180°C inlet temperature and a total heat input of 70 kWth . It uses a two-stage expansion process with hydrofluoroether as the working fluid. A wet cooling tower is used to dissipate the reject heat from the ORC. The two key components of the envisioned system are the trough reflector/receiver and the ORC unit. The optical performance of the mirror elements was investigated with regard to the flux mapping onto the receiver tube. The ORC unit has been tested separately using an electrical oil heater as the heat source. This paper presents results for irradiation capture and intensity over the receiver width of a single trough mirror module. The complete system including trough collectors and ORC has not been in transient operation yet, thus experimental steady-state results of the ORC unit are presented.
International Journal of Optics and Applications, 2013
In this paper ways of using compound parabolic concentrators as primary optical elements for conc... more In this paper ways of using compound parabolic concentrators as primary optical elements for concentrated photovoltaics are evaluated. The problems related to these classical non-imag ing optical elements for photovoltaics applications have been evaluated by modelling different types of linear and point focus concentrators. Particular consideration is given to the issues of manufacturability and cost. The non-uniformity of the flu x resulting at the concentrator exit aperture has been considered and some solutions are proposed in order to reduce adverse effects on performance, as well as to increase the angular tolerance of the system.
The performance of a parabolic trough photovoltaic/thermal collector with a geometric concentrati... more The performance of a parabolic trough photovoltaic/thermal collector with a geometric concentration ratio of 37· is described. Measured results under typical operating conditions show thermal efficiency around 58% and electrical efficiency around 11%, therefore a combined efficiency of 69%. The impact of non-uniform illumination on the solar cells is investigated using purpose built equipment that moves a calibrated solar cell along the line of the receiver and measures short circuit current. The measured illumination flux profile along the length shows significant variation, despite the mirror shape error being less than 1 mm for most of the mirror area. The impact of the illumination nonuniformities due to the shape error, receiver support post shading and gaps between the mirrors is shown to have a significant effect on the overall electrical performance. The flux profile transverse to the receiver length is also investigated. Peak flux intensities are shown to be around 100 suns. The impact on efficiency due to open circuit voltage reduction is discussed.
The Australian National University, Centre for Sustainable Energy Systems (ANU-CSES) has develope... more The Australian National University, Centre for Sustainable Energy Systems (ANU-CSES) has developed a photovoltaic thermal (PV-T) concentrator system. This system is based on its Combined Heat and Power Solar (CHAPS) collector technology. This paper describes a roof mounted 40 kW PV-T concentrator system which was installed during 2003-4. The system comprises eight 24 metre long single axis tracking reflective solar collectors. Mirrors are used to focus light onto high efficiency monocrystalline silicon solar cells. The mirrors are constructed by laminating mirrored glass onto a metal backing, and provide a geometrical concentration ratio of 37x. Heat is removed from the solar cells using a fluid, which flows through a passage in the cell housings. The fluid is then passed through a heat exchanger to provide heat for domestic hot water and room heating. The collector movement is controlled by a microprocessor using an open loop time based algorithm. The annual output of the system is expected to be 50 MWHr of electricity and 100 MWHr of hot water.
ABSTRACT This paper presents component performance results of a new parabolic trough collector ar... more ABSTRACT This paper presents component performance results of a new parabolic trough collector array driving an organic Rankine cycle (ORC) power generation system. The system has been installed in the National Solar Energy Centre at CSIRO Energy Technology in Newcastle, NSW, Australia. It consists of four rows of 18 parabolic mirrors each in a 2×2 matrix with a total aperture area of approximately 132m2 . The absorber tube is a laterally aligned, 40mm copper tube coated with a semi-selective paint and enclosed in a 50mm non-evacuated glass tube to reduce convection losses. The mirror modules, which are light-weight and robust, are made from thin low iron back silvered glass bonded to a sheet steel substrate. They are supported by a box truss on semi circular hoops running on rollers for single axis tracking. The mirror design has been chosen to allow low-cost manufacturing as well as simple commissioning and operation. The ORC unit is a FP6 unit sourced from Freepower Ltd. with a net power output of 6kWel at 180°C inlet temperature and a total heat input of 70 kWth . It uses a two-stage expansion process with hydrofluoroether as the working fluid. A wet cooling tower is used to dissipate the reject heat from the ORC. The two key components of the envisioned system are the trough reflector/receiver and the ORC unit. The optical performance of the mirror elements was investigated with regard to the flux mapping onto the receiver tube. The ORC unit has been tested separately using an electrical oil heater as the heat source. This paper presents results for irradiation capture and intensity over the receiver width of a single trough mirror module. The complete system including trough collectors and ORC has not been in transient operation yet, thus experimental steady-state results of the ORC unit are presented.
International Journal of Optics and Applications, 2013
In this paper ways of using compound parabolic concentrators as primary optical elements for conc... more In this paper ways of using compound parabolic concentrators as primary optical elements for concentrated photovoltaics are evaluated. The problems related to these classical non-imag ing optical elements for photovoltaics applications have been evaluated by modelling different types of linear and point focus concentrators. Particular consideration is given to the issues of manufacturability and cost. The non-uniformity of the flu x resulting at the concentrator exit aperture has been considered and some solutions are proposed in order to reduce adverse effects on performance, as well as to increase the angular tolerance of the system.
The performance of a parabolic trough photovoltaic/thermal collector with a geometric concentrati... more The performance of a parabolic trough photovoltaic/thermal collector with a geometric concentration ratio of 37· is described. Measured results under typical operating conditions show thermal efficiency around 58% and electrical efficiency around 11%, therefore a combined efficiency of 69%. The impact of non-uniform illumination on the solar cells is investigated using purpose built equipment that moves a calibrated solar cell along the line of the receiver and measures short circuit current. The measured illumination flux profile along the length shows significant variation, despite the mirror shape error being less than 1 mm for most of the mirror area. The impact of the illumination nonuniformities due to the shape error, receiver support post shading and gaps between the mirrors is shown to have a significant effect on the overall electrical performance. The flux profile transverse to the receiver length is also investigated. Peak flux intensities are shown to be around 100 suns. The impact on efficiency due to open circuit voltage reduction is discussed.
The Australian National University, Centre for Sustainable Energy Systems (ANU-CSES) has develope... more The Australian National University, Centre for Sustainable Energy Systems (ANU-CSES) has developed a photovoltaic thermal (PV-T) concentrator system. This system is based on its Combined Heat and Power Solar (CHAPS) collector technology. This paper describes a roof mounted 40 kW PV-T concentrator system which was installed during 2003-4. The system comprises eight 24 metre long single axis tracking reflective solar collectors. Mirrors are used to focus light onto high efficiency monocrystalline silicon solar cells. The mirrors are constructed by laminating mirrored glass onto a metal backing, and provide a geometrical concentration ratio of 37x. Heat is removed from the solar cells using a fluid, which flows through a passage in the cell housings. The fluid is then passed through a heat exchanger to provide heat for domestic hot water and room heating. The collector movement is controlled by a microprocessor using an open loop time based algorithm. The annual output of the system is expected to be 50 MWHr of electricity and 100 MWHr of hot water.
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Papers by Joe Coventry