为研究外界因素对风机叶片电阻加热除冰时间的影响规律,以及电阻丝布置方式对融冰过程的影响,该文在多功能人工气候室内对风机叶片进行了电阻加热除冰试验研究,分析了覆冰厚度、环境温度、相对风速和液态水含量(liquid water content,L...为研究外界因素对风机叶片电阻加热除冰时间的影响规律,以及电阻丝布置方式对融冰过程的影响,该文在多功能人工气候室内对风机叶片进行了电阻加热除冰试验研究,分析了覆冰厚度、环境温度、相对风速和液态水含量(liquid water content,LWC)对除冰时间的影响规律,并提出了合理的电阻丝布置方式。结果表明:覆冰厚度较小时,其对除冰时间的影响较为明显,随着覆冰厚度的继续增大,除冰时间无明显差异;除冰时间随加热功率和环境温度的增大而降低,随相对风速和LWC的增大而增大,且不同覆冰厚度下除冰时间随上述因素的变化曲线会有较大不同;叶片尖部电阻丝宜采用弦向布置,根部电阻丝宜采用展向布置;除冰过程中,叶片尖部冰层易发生脱落,根部冰层易被融化。展开更多
This study evaluates the effectiveness of phase change materials(PCMs) inside a storage tank of warm water for solar water heating(SWH) system through the theoretical simulation based on the experimental model of S.Ca...This study evaluates the effectiveness of phase change materials(PCMs) inside a storage tank of warm water for solar water heating(SWH) system through the theoretical simulation based on the experimental model of S.Canbazoglu et al.The model is explained by five fundamental equations for the calculation of various parameters like the effectiveness of PCMs,the mass of hot water,total heat content,and duration of charging.This study simulated eleven PCMs to analyze their effectiveness like Sodium hydrogen phosphate dodecahydrate(SHPD),OM 37,N-Eicosane(NE),Lauric acid(LA),Paraffin wax(PW),OM 48,Paraffin wax C_(20-33)(PW-C20-33),Sodium acetate trihydrate(SAT),Palmitic acid(PA),Myristic acid(MA),and Stearic acid(SA).Among all PCMs,the SHPD has found the highest value of effectiveness factor of 3.27.So,it is the most recommended PCM for the storage tank of the SWH system.The study also includes the melt fraction analysis of all enumerated PCMs corresponding to container materials of stainless steel,glass,aluminum mixed,tin,aluminum,and copper.This melt fraction analysis is performed by making a coding program in the FORTRAN programming language.Through the analysis,copper container material is found to have high melting rate for all PCMs so it is superior to other container materials.展开更多
The effect of melt over-heating on the morphology of Al_9FeNi phase in 2618aluminum alloy with high contents of Fe and Ni and 0.22 wt. percent zirconium has been investigatedby optical microscopy. SEM and TEM. The mec...The effect of melt over-heating on the morphology of Al_9FeNi phase in 2618aluminum alloy with high contents of Fe and Ni and 0.22 wt. percent zirconium has been investigatedby optical microscopy. SEM and TEM. The mechanical properties of 2618 aluminum alloy after hotextrusion and quenching/aging have been tested. The results show: melt over-heating treatment of2618 alloy with high contents of Fe and Ni at 960 deg C led to finer and better-distributedneedle-like Al_9FeNi phase in cast microstructure and fine Al_9FeNi particles after hot extrusion;the grain size of the alloy after hot extrusion could also be refined evidently by alloying ofzirconium; the ambient and high temperature tensile strength and elongation of 2618 alloy have beenapparently enhanced due to fine Al_9FeNi particles and dispersed Al_3Zr as well as fine grain size.展开更多
Experiments were carried out on carburizing and temperature rising of the semi steel melt in a plasma induction furnace.Influence of many factors, such as power supply mode,position of the plasma torch and bottom b...Experiments were carried out on carburizing and temperature rising of the semi steel melt in a plasma induction furnace.Influence of many factors, such as power supply mode,position of the plasma torch and bottom blown gas stirring,on heating efficiency and melt temperature distribution was studied. Melt temperature could be effectively controlled by plasma heating,and carbon content of semi steel melt increased from 1.92 % to 4.58 %, and the utilization rate of carbon reached up to 61.57 % during carburizing of the melt.展开更多
A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine,...A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine, square, triangle and sawtooth waveforms) of the induction coil. Comparison between the results presented here demonstrates the importance of input current shape on the electromagnetic field distribution, coil efficiency, and intensity and structure of generated power in the growth setup.展开更多
文摘为研究外界因素对风机叶片电阻加热除冰时间的影响规律,以及电阻丝布置方式对融冰过程的影响,该文在多功能人工气候室内对风机叶片进行了电阻加热除冰试验研究,分析了覆冰厚度、环境温度、相对风速和液态水含量(liquid water content,LWC)对除冰时间的影响规律,并提出了合理的电阻丝布置方式。结果表明:覆冰厚度较小时,其对除冰时间的影响较为明显,随着覆冰厚度的继续增大,除冰时间无明显差异;除冰时间随加热功率和环境温度的增大而降低,随相对风速和LWC的增大而增大,且不同覆冰厚度下除冰时间随上述因素的变化曲线会有较大不同;叶片尖部电阻丝宜采用弦向布置,根部电阻丝宜采用展向布置;除冰过程中,叶片尖部冰层易发生脱落,根部冰层易被融化。
基金the University Grants Commission (UGC) & Ministry of Human Resource Development (MHRD),Government of India,New Delhi for providing the Junior Research Fellowship (JRF)the Council of Science and Technology,UP (Reference No, CST 3012-dt.26-12-2016) for providing research grants to carry out the work at the institute。
文摘This study evaluates the effectiveness of phase change materials(PCMs) inside a storage tank of warm water for solar water heating(SWH) system through the theoretical simulation based on the experimental model of S.Canbazoglu et al.The model is explained by five fundamental equations for the calculation of various parameters like the effectiveness of PCMs,the mass of hot water,total heat content,and duration of charging.This study simulated eleven PCMs to analyze their effectiveness like Sodium hydrogen phosphate dodecahydrate(SHPD),OM 37,N-Eicosane(NE),Lauric acid(LA),Paraffin wax(PW),OM 48,Paraffin wax C_(20-33)(PW-C20-33),Sodium acetate trihydrate(SAT),Palmitic acid(PA),Myristic acid(MA),and Stearic acid(SA).Among all PCMs,the SHPD has found the highest value of effectiveness factor of 3.27.So,it is the most recommended PCM for the storage tank of the SWH system.The study also includes the melt fraction analysis of all enumerated PCMs corresponding to container materials of stainless steel,glass,aluminum mixed,tin,aluminum,and copper.This melt fraction analysis is performed by making a coding program in the FORTRAN programming language.Through the analysis,copper container material is found to have high melting rate for all PCMs so it is superior to other container materials.
基金The present study was supported by the National Key Basic Research and Development Programme of China (Project No. G1999064909).
文摘The effect of melt over-heating on the morphology of Al_9FeNi phase in 2618aluminum alloy with high contents of Fe and Ni and 0.22 wt. percent zirconium has been investigatedby optical microscopy. SEM and TEM. The mechanical properties of 2618 aluminum alloy after hotextrusion and quenching/aging have been tested. The results show: melt over-heating treatment of2618 alloy with high contents of Fe and Ni at 960 deg C led to finer and better-distributedneedle-like Al_9FeNi phase in cast microstructure and fine Al_9FeNi particles after hot extrusion;the grain size of the alloy after hot extrusion could also be refined evidently by alloying ofzirconium; the ambient and high temperature tensile strength and elongation of 2618 alloy have beenapparently enhanced due to fine Al_9FeNi particles and dispersed Al_3Zr as well as fine grain size.
文摘Experiments were carried out on carburizing and temperature rising of the semi steel melt in a plasma induction furnace.Influence of many factors, such as power supply mode,position of the plasma torch and bottom blown gas stirring,on heating efficiency and melt temperature distribution was studied. Melt temperature could be effectively controlled by plasma heating,and carbon content of semi steel melt increased from 1.92 % to 4.58 %, and the utilization rate of carbon reached up to 61.57 % during carburizing of the melt.
文摘A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine, square, triangle and sawtooth waveforms) of the induction coil. Comparison between the results presented here demonstrates the importance of input current shape on the electromagnetic field distribution, coil efficiency, and intensity and structure of generated power in the growth setup.
