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There is plenty of iron ore with arsenic in China. Because a proven dearsenization technique does not come into existence in now iron making and steel making processes and it is necessary for developing the dearsenization of hot metal technologics. A serial of dearsenization experiments are carried out on electric resistance heated furnace, it's found that arsenic in hot metal can be removed by CaO basis fluxes. X ray qualitative analysis of CaO basis slag after dearsenization revealed that the product of hot metal dearsenization with CaO slag is Ca 3As 2 and the dearsenization reaction is a reducing one. The thermodynamic conditions of dearsenization of hot metal using CaO basis fluxes are that the lower of oxygen fraction pressure of the system and [s] in hot metal, the higher of temperature of the system and basically of the slag, the dearsenization efficiency is better. 相似文献
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In the established model,
the cooling differences are considered between the surface of inner radius and that of
outer radius, and in the transverse direction of thin slab. And the conception for the
effective coefficient of spraying water in continuous casting is firstly put forward.
According to different casting speeds and different cooling zones, different time step
lengths are adopted. In this model the heat transfer differences are thought over among
vertical and curved zones, wide and narrow surfaces an well as angular zone of mould. The
method of the corrected equivalent specific heat is used to deal with latent heat. The
influence of forced convection is considered on heat transfer. Therefore, the model has
higher accuracy and is consistent with the practice. 相似文献
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In order to enhance the heat transfer in the phase change heat storage device, a rectangular cavity filled with metal foam / paraffin wax is made. The melting heat storage experiment of foam metal / wax composite phase change material was carried out in the transverse wall temperature conditions. The temperature change curve is drawn according to different heating temperatures. Both the effects of natural convection in rectangular cavity on temperature distribution and the impact of heat transfer temperature difference on the thermal storage time are analyzed. The results show that the melting process of the paraffin in the body cavity is reinforced by the high thermal conductivity of copper foam. The remaining solid paraffin is accelerated to melt by the natural convection of the liquid paraffin formed near the heating surface; and the greater the heat transfer temperature difference is, the greater the natural convection is and the shorter the time for heat storage is. 相似文献
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FANG Jun_hua PENG Xu_ya 《保鲜与加工》1999,(6):70
Due to the effect of hot island of the city, the temperature is much higher and the urban hot environment is much worse in the city than those in the countryside. In this paper, the total heat difference based on the temperature has been suggested as an evaluation factor and the total heat change quality index as evaluation method to describe the quality of urban hot environment. 相似文献
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Based on the analysis and study on some existed models for two-dimensional Guillotine Cutting-Stock problem, it is pointed out that some kinds of the models may miss some good cutting patterns,and some may result in inadequate solutions because of only considering the patterns with the smallest waste. A kind of revised two-dimensional cutting-stock models are developed,which transform the two-dimensional problem into the one-dimensional one using the dimension-decreasing heuristic method and whose initial patterns are considered comprehensively. In this kind of models, not only the least waste,but also the other constraints,such as the demands and the relative area of the order plates are considered. 相似文献
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The on line hot treatment can not only boost the strength but also gain lower cost. It is usually called tempcore which was developed greatly these years. The process of tempcor art is introduced and the core subject mathematical models is studied. According to the heating exchanging property of screw rod in cooling after rolling.Two mathematical models including beginning cooling model and cooling water amount model are obtained by analysing, deducing theoretically and simplifying mathematically. Its structure is simple and practiced .The parameter of model is obtained from measuring data of work site. It is able to suite the change of work site, so it can be used in practiced controlling. 相似文献
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The river water source heat pump system is an important technique to utilize renewable energy in Chongqing and heat exchanger can influence overall energy efficiency of system obviously. A test was carried out to study the heat transfer efficiency of double pipe heat exchanger with semicircular reentrant tube. It was found that the heat transfer efficiency would increase while curvature of semicircular reentrant tube rose. And when the ratio of R to r was five, heat transfer efficiency for semicircular reentrant tube would be increased 2.5% than that of straight double pipe heat exchanger. Flow, temperature field and heat transfer process of semicircular reentrant tube were simulated with computational fluid dynamics(CFD) tool to study the heat transfer mechanism. The modified RNG κ ε Turbulence Model was adopted to ensure the accuracy of simulation analysis under the situation of rotary flow and great curvature. Thus, it was indicated that there was obvious secondary flow vertex in reentrant tube. And disturbance of vertex on boundary layer was the main reason for which heat transfer efficiency of double pipe heat exchanger would increase as curvature of semi toroidal reentrant tube rose. Based on the experiment and simulation, the recommended curvature for reentrant tube was proposed with the consideration of sediment in river water and heat transfer efficiency of heat exchanger. 相似文献
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为探索黑木耳的热风干燥工艺技术,比较不同热风温度对黑木耳干燥特性的影响,以自然晾晒干燥和冷冻干燥为对照,对热风干燥黑木耳的水分分布、复水性能和抗氧化活性进行分析。结果表明:黑木耳在85 ℃下的热风干燥速率高于55 ℃和70 ℃,干燥过程由升速阶段和降速阶段组成。对干燥动力学模型进行拟合,发现Page模型为最佳干燥动力学模型。低场核磁共振横向弛豫时间曲线显示,热风干燥前黑木耳中的水分以自由水为主;85 ℃热风干燥黑木耳的复水性能略高于55 ℃和70 ℃,显著高于自然晾晒样品(P<0.05)。热风干燥黑木耳的1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力和β-胡萝卜素保护能力均显著高于自然晾晒样品(P<0.05),85 ℃热风干燥黑木耳的DPPH自由基清除能力和β-胡萝卜素保护能力分别为150.6、138.9 μg Trolox/g md。综上所述,85 ℃热风干燥工艺操作简单,可以较好地保持黑木耳干制品的品质,该研究为黑木耳干燥干燥过程中的品质调控提供了理论依据。 相似文献
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玉米/辣椒间作群体对光能利用的研究 总被引:2,自引:1,他引:2
本试验通过玉米/辣椒的三种间作方式即2:3,2:5,2:7对间作群体的光能利用进行研究,结果表明:在群体形成期,三种间作方式行间透光率都有增加,其中2:5间作底部的透光率较小,表明辣椒活动层对光的截获率较高,提高了群体对光的利用程度;间作玉米植株中部与底部的透光率明显高于单作;间作玉米叶面积主要分布在80~200cm高度的空间内,占总叶面积的71.3%,此时辣椒叶层主要分布在30~60cm的空间内,占总叶面积的80.2%。二者占据不同的空间,配置“层次化”,为光的透射创造条件。 相似文献
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为了构建预测木薯茎叶生物量的数学模型,调查了5个木薯品种茎秆的基部、中部、上部茎粗及茎秆长度和各个分枝的基部粗度、长度等形态学指标,并将生物量分为茎秆和分枝两部分,分别探讨这两部分生物量与相关形态指标的关系。通过多种模型的反复拟合比较,结果以主茎复合幂函数与分枝集合函数的统合方程的拟合效果较好,均方根误差RMSE为104.2,相关系数r为0.9110,拟合优度较高。并且本模型的拟合效果明显优于前人提出的预测木薯茎叶生物量的数学模型。 相似文献
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热处理对青枣货架期品质的影响 总被引:5,自引:0,他引:5
以西昌地区的青枣为试材,研究了不同热处理方式对青枣货架期好果率、腐烂指数、失水率和热伤程度的影响。结果表明,适宜条件的热水处理效果最好,其最佳条件为50℃热水处理10min,能显著提高青枣货架期品质,抑制腐烂,提高好果率,延长青枣的货架寿命。 相似文献
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A great quantity of heavy metal cause trouble when the sewage is used in agriculture as fertilizer. An experiment is carried out on green vitriol and sulfur as culture medium, different dosing ratio of the sewage sludge and inoculated or not the sewage sludge, the effect of heavy metal removal by microbe has been studied. It is shown that the microbes nursed under different environment have better effect on the heavy metal removal and the result of experiments is discussed. 相似文献
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热水老化对棉花种子活力及遗传完整性的影响 总被引:1,自引:0,他引:1
[目的]探讨热水老化对棉花种子活力及遗传完整性的影响,检测供试棉花品种对老化抗性差异。[方法]选取3个陆地棉品种(系)种子采用65℃热水进行处理。[结果]随着处理时间的延长,种子活力在30min和40min处理之间有一个明显拐点,随后逐步下降甚至完全失活;电导率呈现先降低后增加的趋势;种子基因组DNA完整性也随之变化,大分子量条带缺失,小分子量条带减弱。[结论]65℃热水处理能够加速种子老化,可用于检测棉花种子抗老化能力;新陆早36号对热水老化抗性最强,799次之,223抗老化性最差。在生产实际中,可以利用此温度处理30min来提高棉花种子活力,从而确保田间出苗率。 相似文献
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仙草中黄酮的热水法提取 总被引:3,自引:0,他引:3
何明祥 《农产品加工.学刊》2008,(8)
利用热水法从仙草中提取总黄酮。采用正交试验设计方法分别对仙草中黄酮提取条件进行了研究;通过试验,考察了料液比、提取温度、提取时间的改变对黄酮提取率的影响。结果表明,提取时间、料液比对黄酮的提取率影响较大,最佳工艺条件为:提取温度85℃,提取时间2.5h,料液比1∶55。 相似文献