The iron content in the galvanized coating of zinc-iron alloy was determined by atomic absorption spectrometry and two kinds of X-ray fluorescence(XRF)methods.Results show that the chemical method exhibits the highest...The iron content in the galvanized coating of zinc-iron alloy was determined by atomic absorption spectrometry and two kinds of X-ray fluorescence(XRF)methods.Results show that the chemical method exhibits the highest accuracy.However,this method presents low detection efficiency and is thus unsuitable for production quality control.Fundamental parameter and empirical coefficient methods in XRF can be used for the quality control of iron content in the galvanized coating of zinc-iron alloys.The repeatability of the two XRF methods was 0.2%and 0.4%,respectively,which were better than that of the chemical method(0.6%).However,the two XRF methods have their own limitations.The accuracy of the two XRF methods depends on the process stability of different units and may be poorer than that of the chemical method.Thus,the use of the two XRF methods should be carefully restricted.展开更多
Demand, supply and consumption of natural gas in ChinaIncreased natural gas demand due to economic development, energy and environmental impactIn China, the available energy resource is rich in coal and lack in oil an...Demand, supply and consumption of natural gas in ChinaIncreased natural gas demand due to economic development, energy and environmental impactIn China, the available energy resource is rich in coal and lack in oil and gas. Because of this special fuel pattern,展开更多
Values and utilization significance of LNG cold energy LNG is a cryogenic liquid mixture made from gas through purification and liquefaction at the temperature of 162℃ .
The main methods of single-phase convection heat transfer enhancement are analyzed in this paper, and the unity of contradiction between heat transfer enhancement and energy consumption(or exergy destruction)is expoun...The main methods of single-phase convection heat transfer enhancement are analyzed in this paper, and the unity of contradiction between heat transfer enhancement and energy consumption(or exergy destruction)is expounded.The thermodynamic relationship between heat(or exergy)transfer efficiency and energy consumption(or exergy destruction)as well as driving forces is established,and a general theoretical principle for single-phase convection heat transfer enhancement is further obtained. The principle shows that temperature gradient field distribution and velocity field distribution constrain each other,and that the optimum heat transfer efficiency can be obtained when they are synergetic.If the level of the synergy of temperature gradient field distribution with velocity field distribution is determined,the relative uniform temperature gradient is required,and vice versa.The principle also shows the relationship of relative temperature gradient with specific heat and coefficient of heat conductivity.The deduced results can be used as a theoretical guidance for single-phase convection heat transfer enhancement and optimum design of heat exchangers.展开更多
文摘The iron content in the galvanized coating of zinc-iron alloy was determined by atomic absorption spectrometry and two kinds of X-ray fluorescence(XRF)methods.Results show that the chemical method exhibits the highest accuracy.However,this method presents low detection efficiency and is thus unsuitable for production quality control.Fundamental parameter and empirical coefficient methods in XRF can be used for the quality control of iron content in the galvanized coating of zinc-iron alloys.The repeatability of the two XRF methods was 0.2%and 0.4%,respectively,which were better than that of the chemical method(0.6%).However,the two XRF methods have their own limitations.The accuracy of the two XRF methods depends on the process stability of different units and may be poorer than that of the chemical method.Thus,the use of the two XRF methods should be carefully restricted.
文摘Demand, supply and consumption of natural gas in ChinaIncreased natural gas demand due to economic development, energy and environmental impactIn China, the available energy resource is rich in coal and lack in oil and gas. Because of this special fuel pattern,
文摘Values and utilization significance of LNG cold energy LNG is a cryogenic liquid mixture made from gas through purification and liquefaction at the temperature of 162℃ .
基金Supported by the National Natural Science Foundation of China(Grant No.20376078)the National Basic Research Program of China("973"Project)(Grant No.2004CCA03100)
文摘The main methods of single-phase convection heat transfer enhancement are analyzed in this paper, and the unity of contradiction between heat transfer enhancement and energy consumption(or exergy destruction)is expounded.The thermodynamic relationship between heat(or exergy)transfer efficiency and energy consumption(or exergy destruction)as well as driving forces is established,and a general theoretical principle for single-phase convection heat transfer enhancement is further obtained. The principle shows that temperature gradient field distribution and velocity field distribution constrain each other,and that the optimum heat transfer efficiency can be obtained when they are synergetic.If the level of the synergy of temperature gradient field distribution with velocity field distribution is determined,the relative uniform temperature gradient is required,and vice versa.The principle also shows the relationship of relative temperature gradient with specific heat and coefficient of heat conductivity.The deduced results can be used as a theoretical guidance for single-phase convection heat transfer enhancement and optimum design of heat exchangers.
