Steady natural convective airflow in a novel type glazing system with integrated semi-transparent... more Steady natural convective airflow in a novel type glazing system with integrated semi-transparent photovoltaic (PV) cells has been analyzed numerically using a stream function vorticity formulation. Based on the resulting numerical predictions, the effects of Rayleigh numbers on airflow patterns and local heat transfer coefficients on vertical glazing surfaces were investigated for Rayleigh numbers in the range of 10 3 Ra 2 Â 10 5. Significant agreement for the Nusselt numbers was observed between numerical simulation results in this study and those of earlier experimental and theoretical results available from the literature. In addition, the effect of air gap thickness in the cavity on the heat transfer through the cavity is evaluated. The optimum thickness of the air layer in this research is found to be in the range of 60–80 mm. This novel glazing system type could not only generate electricity but also achieve potential energy savings by reducing the air conditioning cooling load when applied in subtropical climatic conditions and simultaneously provide visual comfort in the indoor environment.
This study presents a two-dimensional numerical analysis for thermal control strategies on potent... more This study presents a two-dimensional numerical analysis for thermal control strategies on potential energy savings in a double-pane window integrated with see-through a-Si photovoltaic (PV) cells with low-emittance (low-e) coatings. Both heat transmission through the air gap by combined convection and radiation, and air flow patterns within the cavity of the window were considered. The convection-conducting mechanisms in the cavity of the double-pane window have been closely investigated in this paper. Based on numerical predictions, the effect of Rayleigh number on airflow patterns was investigated for low Rayleigh numbers in the range of 103 ⩽ Ra ⩽ 105. The effect of the low-e coatings on the glazing U-value was also explored in this paper. It was found that a large quantity of heat transfer by radiation could be reduced. This novel glazing system could help engineers’ design in more advanced window systems with building-integrated photovoltaic (BIPV) applications in modern buildings.
Façade-integrated photovoltaic/thermal (BiPV/T) technology is a relatively new concept in improvi... more Façade-integrated photovoltaic/thermal (BiPV/T) technology is a relatively new concept in improving the overall energy performance of PV installations in buildings. With the use of wall-mounted water-type PV/T collectors, the system not only generates electricity and hot water simultaneously, but also improves the thermal insulation of the building envelope. A numerical model of this hybrid system was developed by modifying the Hottel–Whillier model, which was originally for the thermal analysis of flat-plate solar thermal collectors. Computer simulation was performed to analyze the system performance. The combined effects of the solar cell packing factor and the water mass flow rate on the thermal and electrical efficiencies were investigated. The simulation results indicated that an optimum water mass flow rate existed in the system through which the desirable integrated energy performance can be achieved.
Investigation on the thermal performance of different lightweight roofing structures and its effe... more Investigation on the thermal performance of different lightweight roofing structures and its effect on space cooling load
Steady natural convective airflow in a novel type glazing system with integrated semi-transparent... more Steady natural convective airflow in a novel type glazing system with integrated semi-transparent photovoltaic (PV) cells has been analyzed numerically using a stream function vorticity formulation. Based on the resulting numerical predictions, the effects of Rayleigh numbers on airflow patterns and local heat transfer coefficients on vertical glazing surfaces were investigated for Rayleigh numbers in the range of 10 3 Ra 2 Â 10 5. Significant agreement for the Nusselt numbers was observed between numerical simulation results in this study and those of earlier experimental and theoretical results available from the literature. In addition, the effect of air gap thickness in the cavity on the heat transfer through the cavity is evaluated. The optimum thickness of the air layer in this research is found to be in the range of 60–80 mm. This novel glazing system type could not only generate electricity but also achieve potential energy savings by reducing the air conditioning cooling load when applied in subtropical climatic conditions and simultaneously provide visual comfort in the indoor environment.
This study presents a two-dimensional numerical analysis for thermal control strategies on potent... more This study presents a two-dimensional numerical analysis for thermal control strategies on potential energy savings in a double-pane window integrated with see-through a-Si photovoltaic (PV) cells with low-emittance (low-e) coatings. Both heat transmission through the air gap by combined convection and radiation, and air flow patterns within the cavity of the window were considered. The convection-conducting mechanisms in the cavity of the double-pane window have been closely investigated in this paper. Based on numerical predictions, the effect of Rayleigh number on airflow patterns was investigated for low Rayleigh numbers in the range of 103 ⩽ Ra ⩽ 105. The effect of the low-e coatings on the glazing U-value was also explored in this paper. It was found that a large quantity of heat transfer by radiation could be reduced. This novel glazing system could help engineers’ design in more advanced window systems with building-integrated photovoltaic (BIPV) applications in modern buildings.
Façade-integrated photovoltaic/thermal (BiPV/T) technology is a relatively new concept in improvi... more Façade-integrated photovoltaic/thermal (BiPV/T) technology is a relatively new concept in improving the overall energy performance of PV installations in buildings. With the use of wall-mounted water-type PV/T collectors, the system not only generates electricity and hot water simultaneously, but also improves the thermal insulation of the building envelope. A numerical model of this hybrid system was developed by modifying the Hottel–Whillier model, which was originally for the thermal analysis of flat-plate solar thermal collectors. Computer simulation was performed to analyze the system performance. The combined effects of the solar cell packing factor and the water mass flow rate on the thermal and electrical efficiencies were investigated. The simulation results indicated that an optimum water mass flow rate existed in the system through which the desirable integrated energy performance can be achieved.
Investigation on the thermal performance of different lightweight roofing structures and its effe... more Investigation on the thermal performance of different lightweight roofing structures and its effect on space cooling load
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