This study proposes a computational framework for developing a multibody dynamics(MBD)model to accurately predict the vibration behavior of front-loading washing machines.The framework integrates component-level exper...This study proposes a computational framework for developing a multibody dynamics(MBD)model to accurately predict the vibration behavior of front-loading washing machines.The framework integrates component-level experiments and mathematical modeling to characterize the dynamic behavior of key components,including the free-stroke damper,connecting bushing,and gasket,which significantly influence the machine's vibration.Simplified,yet precise,mathematical models were developed and validated against experimental data to represent these components'dynamic characteristics.The validated models were then integrated into a comprehensive MBD model of a front-loading washing machine.This model was further verified by comparing its predicted vibrations with experimental results obtained from actual washing machines.A parametric study assessed the model's accuracy under various unbalanced mass conditions and revolutions per minute ranges,which revealed that the model is capable of generalization across different operating scenarios.Although some errors remain in specific cases involving phase differences,the overall average error is 20.11%,with a standard deviation of 4.10%.These results demonstrate that the proposed framework effectively captures the vibration behavior of front-loading washing machines,offering a reliable tool for enhancing design and operational efficiency.展开更多
The extensive use of traditional cooking and heating stoves to meet domestic requirements creates a serious problem of indoor and outdoor air pollution.This study reports the impacts of two fuel feeding methods-front-...The extensive use of traditional cooking and heating stoves to meet domestic requirements creates a serious problem of indoor and outdoor air pollution.This study reports the impacts of two fuel feeding methods-front-loading and top-loading on the thermal and emissions performance of a modern coal-fired water-heating and cooking stove using a contextual test sequence that replicates typical patterns of domestic use.Known as a low-pressure boiler,when this stove was fueled with raw coal,the findings indicate that front-loading the fuel,which devolatilizes the new fuel gradually,produced consistently higher space heating efficiency and lower emission factors than top-loading the same stove,which devolatilizes new fuel all at once.Comparing the performance at both high and low power gave the similar results:front-loading with raw coal produced consistently better results than top-loading.The average water heating efficiency when front-loading was(58.6±2.3)%and(53.4±1.8)%for top-loading.Over the sixteen-hour test sequence,front-loading produced 22%lower emissions of PM2.5(3.9±0.6)mg/MJNET than top-loading(4.7±0.9)mg/MJNET.The same pattern was observed for carbon monoxide and the CO/CO2 ratio.CO was reduced from(5.0±0.4)g/MJNET to(4.1±0.5)g/MJNET.The combustion efficiency(CO/CO2 ratio)improved from(8.2±0.8)%to(6.6±0.6)%.Briquetted semi-coked coal briquettes are promoted as a raw coal substitute,and the tests were replicated using this fuel.Again,the same pattern of improved performance was observed.Front loading produced 3.5%higher heating efficiency,10%lower CO and a 0.9%lower CO/CO2 ratio.It is concluded that,compared with top loading,the manufacturers recommended front-loading refueling behavior delivered better thermal,emissions and combustion performance under all test conditions with those two fuels.展开更多
文摘This study proposes a computational framework for developing a multibody dynamics(MBD)model to accurately predict the vibration behavior of front-loading washing machines.The framework integrates component-level experiments and mathematical modeling to characterize the dynamic behavior of key components,including the free-stroke damper,connecting bushing,and gasket,which significantly influence the machine's vibration.Simplified,yet precise,mathematical models were developed and validated against experimental data to represent these components'dynamic characteristics.The validated models were then integrated into a comprehensive MBD model of a front-loading washing machine.This model was further verified by comparing its predicted vibrations with experimental results obtained from actual washing machines.A parametric study assessed the model's accuracy under various unbalanced mass conditions and revolutions per minute ranges,which revealed that the model is capable of generalization across different operating scenarios.Although some errors remain in specific cases involving phase differences,the overall average error is 20.11%,with a standard deviation of 4.10%.These results demonstrate that the proposed framework effectively captures the vibration behavior of front-loading washing machines,offering a reliable tool for enhancing design and operational efficiency.
基金This research was supported by the National Natural Science Foundation of China(Grant No.51806242)the Chinese Universities Scientific Fund(No.2019TC010)+3 种基金the Chinese Universities Scientific Fund-Special Project for"Double First-Class"Initiative of College of Engineering,China Agricultural University,"the Characteristics of Thermal and Mass Flow for Clean Space-heating of Rural Households using Biofuels"the Agricultural Product Quality Inspection Bureau,Ministry of Agriculture and Rural Affairs,China,Agricultural Industry Standard Development Project-"Determination method of major atmospheric pollutants from rural household stoves"(No.181721301092371112)the bilateral China-South Africa MoST-NRF joint project“Development of Scientifically Robust and Culturally Appropriate Metrics and Protocols for Evaluating Clean(Combustion)Cooking Stoves”,sponsored by Ministry of Science and Technology,ChinaInvestigation on South-South Cooperation in Climate Change through Clean Stove Alliance,sponsored by Ministry of Ecology and Environment and Administrative Center for China's Agenda 21(No.0201835).
文摘The extensive use of traditional cooking and heating stoves to meet domestic requirements creates a serious problem of indoor and outdoor air pollution.This study reports the impacts of two fuel feeding methods-front-loading and top-loading on the thermal and emissions performance of a modern coal-fired water-heating and cooking stove using a contextual test sequence that replicates typical patterns of domestic use.Known as a low-pressure boiler,when this stove was fueled with raw coal,the findings indicate that front-loading the fuel,which devolatilizes the new fuel gradually,produced consistently higher space heating efficiency and lower emission factors than top-loading the same stove,which devolatilizes new fuel all at once.Comparing the performance at both high and low power gave the similar results:front-loading with raw coal produced consistently better results than top-loading.The average water heating efficiency when front-loading was(58.6±2.3)%and(53.4±1.8)%for top-loading.Over the sixteen-hour test sequence,front-loading produced 22%lower emissions of PM2.5(3.9±0.6)mg/MJNET than top-loading(4.7±0.9)mg/MJNET.The same pattern was observed for carbon monoxide and the CO/CO2 ratio.CO was reduced from(5.0±0.4)g/MJNET to(4.1±0.5)g/MJNET.The combustion efficiency(CO/CO2 ratio)improved from(8.2±0.8)%to(6.6±0.6)%.Briquetted semi-coked coal briquettes are promoted as a raw coal substitute,and the tests were replicated using this fuel.Again,the same pattern of improved performance was observed.Front loading produced 3.5%higher heating efficiency,10%lower CO and a 0.9%lower CO/CO2 ratio.It is concluded that,compared with top loading,the manufacturers recommended front-loading refueling behavior delivered better thermal,emissions and combustion performance under all test conditions with those two fuels.
