This research studies the numerical modelling using computational fluid dynamics with a k-Epsilon turbulence model to analyze airflow behaviors inside the alternative compared with conventional air ductwork combined w...This research studies the numerical modelling using computational fluid dynamics with a k-Epsilon turbulence model to analyze airflow behaviors inside the alternative compared with conventional air ductwork combined with a comprehensive analysis of the economic parameter created by the author called Reveal Comparative Advantage Cost index.All alternative air ductwork has lower pressure drop and a higher ability to maintain the temperature inside,showing that alternative air duct systems have a significant advantage over conventional air ductwork.The fabric ductwork has a lower pressure drop than galvanized steel perforated ductwork,which is 69.15%.The pre-insulated ductwork can keep the best temperature inside,with a different temperature value between the air inlet and air outlet of 0.06℃.The Reveal Comparative Advantage Cost of construction costs of the galvanized steel ductwork and the galvanized steel perforated ductwork are 1.02 and 1.06,which means the conventional air ductwork is initially cost-effective in terms of investment and operating costs.However,alternative air ductwork is the better option for long-term use.They have cost-effective electrical energy and maintenance costs with a high Reveal Comparative Advantage Cost index.Significantly,the pre-insulated ductwork has the Reveal Comparative Advantage Cost index of maintenance,electrical energy,and construction costs of 1.38,1.09,and 0.95,respectively.The results of the airflow behaviors study combined with the Reveal Comparative Advantage Cost index study show that the galvanized steel perforated ductwork is not a selectivity that qualifies either for airflow behaviors or is unsuitable for investment.Pre-insulated ductwork is the appropriate option due to the high airflow behaviors and cost,which makes it suitable for investment.However,the Thailand Authority should develop alternative air ductwork Thai standards for engineering design and safety building.展开更多
A validated CFD model is employed to predict the airflow behavior in an impinging jet ventilation(IJV)room with cool,isothermal or warm jets.By using the numerical results,the influences of jet discharge height,supply...A validated CFD model is employed to predict the airflow behavior in an impinging jet ventilation(IJV)room with cool,isothermal or warm jets.By using the numerical results,the influences of jet discharge height,supply grille shape and room height on the jet flow behavior as well as the draught discomfort are analyzed for IJV operating in heating scenarios.The results indicate that the warm supply jet of IJV rises upward to the ceiling after spreading along the floor for a certain distance due to thermal buoyancy,resulting in a limited dispersion area,while the cool and isothermal jets of IJV always spread along the whole floor.When IJV is used for space heating,the lower the jet discharge height,the farther the supply air spreads along the floor,and the supply grille shape and room height almost have no effect on the air dispersion area.The results also show that the energy-efficient advantage of IJV in its heating mode compared to the mixing ventilation(MV)system is more remarkable in higher rooms.Moreover,there is a risk of draught discomfort in IJV heating rooms and it is recommended to wear socks to avoid this discomfort.展开更多
基金funded by Kasetsart University through the Graduate School Fellowship Program,year 2021.
文摘This research studies the numerical modelling using computational fluid dynamics with a k-Epsilon turbulence model to analyze airflow behaviors inside the alternative compared with conventional air ductwork combined with a comprehensive analysis of the economic parameter created by the author called Reveal Comparative Advantage Cost index.All alternative air ductwork has lower pressure drop and a higher ability to maintain the temperature inside,showing that alternative air duct systems have a significant advantage over conventional air ductwork.The fabric ductwork has a lower pressure drop than galvanized steel perforated ductwork,which is 69.15%.The pre-insulated ductwork can keep the best temperature inside,with a different temperature value between the air inlet and air outlet of 0.06℃.The Reveal Comparative Advantage Cost of construction costs of the galvanized steel ductwork and the galvanized steel perforated ductwork are 1.02 and 1.06,which means the conventional air ductwork is initially cost-effective in terms of investment and operating costs.However,alternative air ductwork is the better option for long-term use.They have cost-effective electrical energy and maintenance costs with a high Reveal Comparative Advantage Cost index.Significantly,the pre-insulated ductwork has the Reveal Comparative Advantage Cost index of maintenance,electrical energy,and construction costs of 1.38,1.09,and 0.95,respectively.The results of the airflow behaviors study combined with the Reveal Comparative Advantage Cost index study show that the galvanized steel perforated ductwork is not a selectivity that qualifies either for airflow behaviors or is unsuitable for investment.Pre-insulated ductwork is the appropriate option due to the high airflow behaviors and cost,which makes it suitable for investment.However,the Thailand Authority should develop alternative air ductwork Thai standards for engineering design and safety building.
基金supported by the National Natural Science Foundation of China(No.51278094 and No.51478098)the Innovation Foundation of Shanghai Education Commission(No.13ZZ054)the Natural Science Foundation of Jiangsu Province,China(No.BK20161336).
文摘A validated CFD model is employed to predict the airflow behavior in an impinging jet ventilation(IJV)room with cool,isothermal or warm jets.By using the numerical results,the influences of jet discharge height,supply grille shape and room height on the jet flow behavior as well as the draught discomfort are analyzed for IJV operating in heating scenarios.The results indicate that the warm supply jet of IJV rises upward to the ceiling after spreading along the floor for a certain distance due to thermal buoyancy,resulting in a limited dispersion area,while the cool and isothermal jets of IJV always spread along the whole floor.When IJV is used for space heating,the lower the jet discharge height,the farther the supply air spreads along the floor,and the supply grille shape and room height almost have no effect on the air dispersion area.The results also show that the energy-efficient advantage of IJV in its heating mode compared to the mixing ventilation(MV)system is more remarkable in higher rooms.Moreover,there is a risk of draught discomfort in IJV heating rooms and it is recommended to wear socks to avoid this discomfort.
基金supported by the Key Laboratory of Icing and Anti/de-icing of CARDC (No. IADL 20220107)the National Science and Technology Major Special Funds of China (No.J2019-Ⅲ-0010-0054)the National Natural Science Foundation of China (No. 52076164)。
