Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was inve...Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was investigated. It was found that the contact resistance increased due to the Joule beating, and that increased contact resistance produced more Joule heating; this mutual action causes the connector to lose efficiency. The thermal distribution in the connector was analyzed using finite element method （FEM）. The failure mechanism is discussed. It provides basis for improving the structure. The conclusion was verified by experimental results.展开更多
A real-time sensing of the molecular distillation process temperature by a FLUKE brand thermograph Ti50 IR FlexCam and thermography technique was realized. After completion of the molecular distillation, three propert...A real-time sensing of the molecular distillation process temperature by a FLUKE brand thermograph Ti50 IR FlexCam and thermography technique was realized. After completion of the molecular distillation, three properties of heat transport chain cuts and residues obtained in the process were estimated by Differential Scanning Calorimetry （DSC） （specific heat, enthalpy, thermal conductivity）. These properties are of great importance for improving oil characterization and for future modeling and simulation of the molecular distillation process. The results show that through the method of Differential Scanning Calorimetry, profiles have been obtained from the variation of specific heat, enthalpy and thermal condutivity as a function of temperature for samples of cuts from the distillation （ASTM D-2892） and fractions of distillate and residue from the process of molecular distillation.展开更多
We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derive...We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derived and studied in detail. The superconducting lead influences the heat generation significantly. An obvious step appears in Q - eV characteristics and the iocation of this step is related with the phonon frequency ωo. The heat generations exhibit very different behaviour in the condition eV 〈 △ and eV 〉 △ due to different tunneling mechanism. From the study of Q - eVg curves, there is an extra peak as eV 〉 △. The difference in this two cases is also shown in Q - ωo curve, an extra peak emerges as eV 〉 △.展开更多
The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for u...The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for underground water. In this model, a heater installed within the heat tank represented sources of waste heat as energy input for finding appropriate conditions of the 10 L pump model. The system operation had five stages： heating, pumping, vapor flow, cooling, and water suction. The overall water heads of 3, 4.5, 6 and 7.5 m were tested. At the same time, it was found that the pump with 50% air volume is sufficient for pumping water to a desired level. In the experiment, the temperatures in the heating and pumping stages were 100-103 ℃and 80-90 ℃, respectively. The pressure in the pumping stage was 12-18 kPa, and the pressure in the suction stage was about-80 kPa, sufficient for the best performance. It could pump 170 L of water at a 2 m suction head, 120 L at a 3.5 m suction head, 100 L at a 5 m suction head, and 65 L at a 6.5 m suction head in 2 h. A mathematical model for larger pumps was also presented, which operates nearly the same as the present system. Economic analysis of the 10 L pump was also included.展开更多
The paper presents experimental and theoretical studies of non-thermal plasma assisted reforming of liquid ethanol into hydrogen-rich syngas in dynamic plasma-liquid systems （PLS） using electric DC and pulsed discha...The paper presents experimental and theoretical studies of non-thermal plasma assisted reforming of liquid ethanol into hydrogen-rich syngas in dynamic plasma-liquid systems （PLS） using electric DC and pulsed discharges in a gas channel with liquid wall （DGCLW） and DC discharge in a reverse vortex gas flow of Tornado type with ＂liquid＂ electrode （TORNADO-LE）. Results of experiments show the energy efficiency of plasma-chemical conversion of ethanol in studied systems. Results of model calculations explain the kinetic mechanism of non-equilibrium plasma-chemical transformations in different conditions. The proposed technique of plasma-fuel reforming can be used in alternative biofuels combustion technologies in advanced diesel engines and power plants.展开更多
Over the last three decades, the Tibetan Plateau has exhibited a significant increase in air temperature and a significant decrease in wind speed. How the surface heat source has changed is an important issue in monso...Over the last three decades, the Tibetan Plateau has exhibited a significant increase in air temperature and a significant decrease in wind speed. How the surface heat source has changed is an important issue in monsoon research. Based on routine meteorological data, this study investigates the differences between methods for estimating trends in surface sensible heat flux on the Tibetan Plateau for the period 1984-2006. One is a physical method based on micro-meteorological theory and experi- ments, and takes into account both atmospheric stability and thermal roughness length. The other approach includes conven- tional empirical methods that assume the heat transfer coefficient is a constant value or a simple function of wind speed. The latter method is used widely in climatologic studies. Results from the physical method show that annual mean sensible heat flux has weakened by 2% per decade, and flux seasonal mean has weakened by -2%--4% except in winter. The two commonly used empirical methods showed high uncertainties in heat flux trend estimates, although they produced similar climatologies. Annual mean heat flux has weakened by 7% per decade when a fixed transfer coefficient is used, whereas the trend is negligible when the transfer coefficient is assumed a function of wind speed. Conventional empirical methods may therefore misrepresent the trend in sensible heat flux.展开更多
We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss meas...We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss measurement of Re BCO wires,so-called the second generation(2G)HTS wires.Compared with conventional calorimetric methods,the suggested method is both free of electromagnetic disturbance,magnetic field,and fast as well as simple.Self-field AC losses are measured by the optical FBG method and the conventional lock-in-amplifier(LIA)technique,respectively.The results show that the measured AC loss is in good agreement with those measured by the electric method,thus the presented calorimetric method would be available for measuring the AC loss of 2G wire and is expected to be generalized for the measurement of AC loss or thermal performances of HTS bulk.展开更多
We study the heat generation in quantum dot system with Fano resonance by nonequilibrium Green＇s functions method. The Fano resonance influences the heat generation significantly. As increases, the heat generation d...We study the heat generation in quantum dot system with Fano resonance by nonequilibrium Green＇s functions method. The Fano resonance influences the heat generation significantly. As increases, the heat generation decreases gradually. From the study of Q-eV curves, we llnd that the linewidth function F has huge influence on the heat generation. The Q-eV curves display obvious steps when the linewidth function is small. However, these steps disappear with F increasing. As the source-drain bias eV increases, the Q-eVg curves also display interesting behaviors.展开更多
文摘Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was investigated. It was found that the contact resistance increased due to the Joule beating, and that increased contact resistance produced more Joule heating; this mutual action causes the connector to lose efficiency. The thermal distribution in the connector was analyzed using finite element method （FEM）. The failure mechanism is discussed. It provides basis for improving the structure. The conclusion was verified by experimental results.
文摘A real-time sensing of the molecular distillation process temperature by a FLUKE brand thermograph Ti50 IR FlexCam and thermography technique was realized. After completion of the molecular distillation, three properties of heat transport chain cuts and residues obtained in the process were estimated by Differential Scanning Calorimetry （DSC） （specific heat, enthalpy, thermal conductivity）. These properties are of great importance for improving oil characterization and for future modeling and simulation of the molecular distillation process. The results show that through the method of Differential Scanning Calorimetry, profiles have been obtained from the variation of specific heat, enthalpy and thermal condutivity as a function of temperature for samples of cuts from the distillation （ASTM D-2892） and fractions of distillate and residue from the process of molecular distillation.
基金Supported by the Scientific Research Fund of Hunan Provincial Education Department under Grant No. 10B022Hunan Provincial Natural Science Foundation of China under Grant No. 11JJ4005
文摘We investigate the heat generation induced by electrical current in a normal-metal-molecular quantum dot-superconductor （NDS） system. By using nonequilibrium Green＇s function method, the heat generation Q is derived and studied in detail. The superconducting lead influences the heat generation significantly. An obvious step appears in Q - eV characteristics and the iocation of this step is related with the phonon frequency ωo. The heat generations exhibit very different behaviour in the condition eV 〈 △ and eV 〉 △ due to different tunneling mechanism. From the study of Q - eVg curves, there is an extra peak as eV 〉 △. The difference in this two cases is also shown in Q - ωo curve, an extra peak emerges as eV 〉 △.
基金the financial support provided by National Research Council of Thailand and the Energy Technology Division, School of Energy Environment and Materials, King Mongkut’s University of Technology Thonburisupported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission
文摘The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for underground water. In this model, a heater installed within the heat tank represented sources of waste heat as energy input for finding appropriate conditions of the 10 L pump model. The system operation had five stages： heating, pumping, vapor flow, cooling, and water suction. The overall water heads of 3, 4.5, 6 and 7.5 m were tested. At the same time, it was found that the pump with 50% air volume is sufficient for pumping water to a desired level. In the experiment, the temperatures in the heating and pumping stages were 100-103 ℃and 80-90 ℃, respectively. The pressure in the pumping stage was 12-18 kPa, and the pressure in the suction stage was about-80 kPa, sufficient for the best performance. It could pump 170 L of water at a 2 m suction head, 120 L at a 3.5 m suction head, 100 L at a 5 m suction head, and 65 L at a 6.5 m suction head in 2 h. A mathematical model for larger pumps was also presented, which operates nearly the same as the present system. Economic analysis of the 10 L pump was also included.
文摘The paper presents experimental and theoretical studies of non-thermal plasma assisted reforming of liquid ethanol into hydrogen-rich syngas in dynamic plasma-liquid systems （PLS） using electric DC and pulsed discharges in a gas channel with liquid wall （DGCLW） and DC discharge in a reverse vortex gas flow of Tornado type with ＂liquid＂ electrode （TORNADO-LE）. Results of experiments show the energy efficiency of plasma-chemical conversion of ethanol in studied systems. Results of model calculations explain the kinetic mechanism of non-equilibrium plasma-chemical transformations in different conditions. The proposed technique of plasma-fuel reforming can be used in alternative biofuels combustion technologies in advanced diesel engines and power plants.
基金supported by National Natural Science Foundation of China (Grant Nos. 40875009, 40810059006)Key Innovation Project of Chinese Academy of Sciences (Grant No. KZCX2-YW-Q11-01),"100-Talent" Program of Chinese Academy of Sciences
文摘Over the last three decades, the Tibetan Plateau has exhibited a significant increase in air temperature and a significant decrease in wind speed. How the surface heat source has changed is an important issue in monsoon research. Based on routine meteorological data, this study investigates the differences between methods for estimating trends in surface sensible heat flux on the Tibetan Plateau for the period 1984-2006. One is a physical method based on micro-meteorological theory and experi- ments, and takes into account both atmospheric stability and thermal roughness length. The other approach includes conven- tional empirical methods that assume the heat transfer coefficient is a constant value or a simple function of wind speed. The latter method is used widely in climatologic studies. Results from the physical method show that annual mean sensible heat flux has weakened by 2% per decade, and flux seasonal mean has weakened by -2%--4% except in winter. The two commonly used empirical methods showed high uncertainties in heat flux trend estimates, although they produced similar climatologies. Annual mean heat flux has weakened by 7% per decade when a fixed transfer coefficient is used, whereas the trend is negligible when the transfer coefficient is assumed a function of wind speed. Conventional empirical methods may therefore misrepresent the trend in sensible heat flux.
基金supported by the National Natural Science Foundation of China(Grant No.51477053)the Beijing Education Commissions(Grant No.GJ2013009)
文摘We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss measurement of Re BCO wires,so-called the second generation(2G)HTS wires.Compared with conventional calorimetric methods,the suggested method is both free of electromagnetic disturbance,magnetic field,and fast as well as simple.Self-field AC losses are measured by the optical FBG method and the conventional lock-in-amplifier(LIA)technique,respectively.The results show that the measured AC loss is in good agreement with those measured by the electric method,thus the presented calorimetric method would be available for measuring the AC loss of 2G wire and is expected to be generalized for the measurement of AC loss or thermal performances of HTS bulk.
基金Supported by the National Natural Science Foundation of China under Grant No.11147189Hunan Provincial Natural Science Foundation of China under Grant Nos.11JJ4005,11JJ9018the the Scientific Research Fund of Hunan Provincial Education Department,China under Grant No.10B022
文摘We study the heat generation in quantum dot system with Fano resonance by nonequilibrium Green＇s functions method. The Fano resonance influences the heat generation significantly. As increases, the heat generation decreases gradually. From the study of Q-eV curves, we llnd that the linewidth function F has huge influence on the heat generation. The Q-eV curves display obvious steps when the linewidth function is small. However, these steps disappear with F increasing. As the source-drain bias eV increases, the Q-eVg curves also display interesting behaviors.
