This paper collects and synthesizes the technical requirements, implementation, and validation methods for quasi-steady agent-based simulations of interconnectionscale models with particular attention to the integrati...This paper collects and synthesizes the technical requirements, implementation, and validation methods for quasi-steady agent-based simulations of interconnectionscale models with particular attention to the integration of renewable generation and controllable loads. Approaches for modeling aggregated controllable loads are presented and placed in the same control and economic modeling framework as generation resources for interconnection planning studies. Model performance is examined with system parameters that are typical for an interconnection approximately the size of the Western Electricity Coordinating Council(WECC) and a control area about 1/100 the size of the system. These results are used to demonstrate and validate the methods presented.展开更多
Advances in material science and engineering are critical to the development of economically viable technologies to address some of the grand socio-economic challenges of the twenty first century.Materials are at the ...Advances in material science and engineering are critical to the development of economically viable technologies to address some of the grand socio-economic challenges of the twenty first century.Materials are at the core展开更多
Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water reso...Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water resources. The efficiency and productivity of these systems are however low, in part because the heat of evaporation has to be transferred as waste heat to ambient air during condensation. In order to maximize energy regeneration during condensation we propose an educator based system that lowers the evaporation process temperature by reducing pressure. The feasibility of the educator assisted passive solar desalination system is investigated using a detailed computational fluid dynamics analysis complemented by experiments. The study focuses in particular on the ability of the new design to lower the required evaporation temperature and thereby reduce the energy intensity of the process. Two configurations, with open and closed educator, are investigated and a detailed analysis of the thermofluid processes is presented. The configuration with a closed educator installed outside the evaporation chamber shows very promising performance. The proposed system can maintain the maximum temperature and pressure in theevaporation chamber below the desirable temperature and pressure thresholds （30 ℃ and 5 kPa）. The analysis and experimental data also show it is possible to further reduce energy requirements by reducing the motive water flow rates.展开更多
Numerical aspects of a pore scale model are investigated for the simulation of catalyst layers of polymer electrolyte membrane fuel cells.Coupled heat,mass and charged species transport together with reaction kinetics...Numerical aspects of a pore scale model are investigated for the simulation of catalyst layers of polymer electrolyte membrane fuel cells.Coupled heat,mass and charged species transport together with reaction kinetics are taken into account using parallelized finite volume simulations for a range of nanostructured,computationally reconstructed catalyst layer samples.The effectiveness of implementing deflation as a second stage preconditioner generally improves convergence and results in better convergence behavior than more sophisticated first stage pre-conditioners.This behavior is attributed to the fact that the two stage preconditioner updates the preconditioning matrix at every GMRES restart,reducing the stalling effects that are commonly observed in restarted GMRES when a single stage preconditioner is used.In addition,the effectiveness of the deflation preconditioner is independent of the number of processors,whereas the localized block ILU preconditioner deteriorates in quality as the number of processors is increased.The total number of GMRES search directions required for convergence varies considerably depending on the preconditioner,but also depends on the catalyst layer microstructure,with low porosity microstructures requiring a smaller number of iterations.The improved model and numerical solution strategy should allow simulations for larger computational domains and improve the reliability of the predicted transport parameters.The preconditioning strategies presented in the paper are scalable and should prove effective for massively parallel simulations of other problems involving nonlinear equations.展开更多
文摘This paper collects and synthesizes the technical requirements, implementation, and validation methods for quasi-steady agent-based simulations of interconnectionscale models with particular attention to the integration of renewable generation and controllable loads. Approaches for modeling aggregated controllable loads are presented and placed in the same control and economic modeling framework as generation resources for interconnection planning studies. Model performance is examined with system parameters that are typical for an interconnection approximately the size of the Western Electricity Coordinating Council(WECC) and a control area about 1/100 the size of the system. These results are used to demonstrate and validate the methods presented.
文摘Advances in material science and engineering are critical to the development of economically viable technologies to address some of the grand socio-economic challenges of the twenty first century.Materials are at the core
基金provided in part by the Deanship of Scientific Research, King Abdulaziz University, Jeddah, under Grant No. (1-135-36-Hi Ci)
文摘Greenhouse solar-energy driven desalination technology is potentially well suited for supplying water and small scale irrigation in remote and/or rural areas, and for avoiding over-exploitation of available water resources. The efficiency and productivity of these systems are however low, in part because the heat of evaporation has to be transferred as waste heat to ambient air during condensation. In order to maximize energy regeneration during condensation we propose an educator based system that lowers the evaporation process temperature by reducing pressure. The feasibility of the educator assisted passive solar desalination system is investigated using a detailed computational fluid dynamics analysis complemented by experiments. The study focuses in particular on the ability of the new design to lower the required evaporation temperature and thereby reduce the energy intensity of the process. Two configurations, with open and closed educator, are investigated and a detailed analysis of the thermofluid processes is presented. The configuration with a closed educator installed outside the evaporation chamber shows very promising performance. The proposed system can maintain the maximum temperature and pressure in theevaporation chamber below the desirable temperature and pressure thresholds （30 ℃ and 5 kPa）. The analysis and experimental data also show it is possible to further reduce energy requirements by reducing the motive water flow rates.
基金the Natural Science and Engineering Research Council(NSERC)Discovery Grant program and the Canada Research Chairs Program.
文摘Numerical aspects of a pore scale model are investigated for the simulation of catalyst layers of polymer electrolyte membrane fuel cells.Coupled heat,mass and charged species transport together with reaction kinetics are taken into account using parallelized finite volume simulations for a range of nanostructured,computationally reconstructed catalyst layer samples.The effectiveness of implementing deflation as a second stage preconditioner generally improves convergence and results in better convergence behavior than more sophisticated first stage pre-conditioners.This behavior is attributed to the fact that the two stage preconditioner updates the preconditioning matrix at every GMRES restart,reducing the stalling effects that are commonly observed in restarted GMRES when a single stage preconditioner is used.In addition,the effectiveness of the deflation preconditioner is independent of the number of processors,whereas the localized block ILU preconditioner deteriorates in quality as the number of processors is increased.The total number of GMRES search directions required for convergence varies considerably depending on the preconditioner,but also depends on the catalyst layer microstructure,with low porosity microstructures requiring a smaller number of iterations.The improved model and numerical solution strategy should allow simulations for larger computational domains and improve the reliability of the predicted transport parameters.The preconditioning strategies presented in the paper are scalable and should prove effective for massively parallel simulations of other problems involving nonlinear equations.
