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Flame temperature was measured by using a compensated finewire thermocouple.


The thermocouple junctions lay on two mutually perpendicular lines parallel to the bases of the cylinder and crossing at its axis.


The position of the transition region was determined from the results of measurement of the local heat flux by calorimetric thermocouple converters.


The subsequent temperature response in the metal is measured by a tiny thermocouple just underneath the (contact) surface.


It is shown that this system keeps a high sensitivity to the sample's magnetic moment and is insensitive to the signals produced by the sample holder and thermocouple due to the compensation of signals in all the coils.

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 In previous papers on transient thermocouple for high gas stream temperature measurements, it was assumed that thermal inertia coefficient of the probe is not variable with wire temperature, and that thermal radiation from the probe may be negligible. But our analysis shows that these methods would make the extrapolated temperature to be greatly underestimated.In this paper, for ChromelAlumel transient thermocouple used in our experiments, we present a new extrapolation method for determining high... In previous papers on transient thermocouple for high gas stream temperature measurements, it was assumed that thermal inertia coefficient of the probe is not variable with wire temperature, and that thermal radiation from the probe may be negligible. But our analysis shows that these methods would make the extrapolated temperature to be greatly underestimated.In this paper, for ChromelAlumel transient thermocouple used in our experiments, we present a new extrapolation method for determining high gas stream temperature. Therein, according to the experimental data of the specific heat of thermocouple materials, it is assumed that thermal inertia coefficient T varies with wire temperature, and that the variation follows T=T0 (1+at). And radiation effect may also be included. For gas stream temperature up to 2500℃ (velocity about 100m/sec.), the new method gives satisfactory results (errors within±6% as compared with standard values). In our experiments, it is found mat the size of probe thermojuction effects greatly on the extrapolated results. It is also found that the application of the convection heat transfer coefficient a determined by means of a transient thermocouple can make more accurate radiation correction for a steady thermocouple with same size.  以前有关高温气流温度测量的动态热偶法的文章都假定，探头的热惯性系数不随丝温变化，且探头的热辐射可忽略不计。可是我们的分析表明，这样做会使外推出的气流温度大为偏低。本文对于我们实验中使用的镍铬－镍铝热电偶，提出了一种新的推算高温气流温度的办法。其中根据热偶材料的比热实验数据，假定热惯性系数Ｔ按Ｔ＝Ｔｏ（１＋ａｔ）规律随丝温变化，方法中也可考虑辐射影响。对于最高达２５００℃的气流温度（速度约１００米／秒），新推算方法给出了令人满意的结果（和标准值比较误差在±６％以内）。我们在实验中发现，探头热结点尺寸对于推算结果有很大影响；还发现，采用动态热偶法实测的对流传热系数α，可以使我们能对同尺寸的稳态热偶作出更精确的辐射修正。  As is well known, it is necessary to make correction for tube surface temperature measured by pyrometer. Because the reflected radiation has much effect on this temperature, the geometric factor considering the reflected radiation is an important quantity in the temperature correction. This paper presents a new method for calculation of geometric factor F. Based on local angle coefficient, the geometric factor F is obtained by calculating the average angle coefficient in the circle of vision field. As an example,... As is well known, it is necessary to make correction for tube surface temperature measured by pyrometer. Because the reflected radiation has much effect on this temperature, the geometric factor considering the reflected radiation is an important quantity in the temperature correction. This paper presents a new method for calculation of geometric factor F. Based on local angle coefficient, the geometric factor F is obtained by calculating the average angle coefficient in the circle of vision field. As an example, the geometric factors for the Topsφe's converter and the Lummus' cracking furnace have been calculated, and by comparison of the calculated values of geometric factors for the Topsφe's converter with those suggested good agreement between them has been found. Based on the presented geometric factor in this paper, the corrected values for the measured temperature by pyrometer agrees with measured temperature by armor thermocouple.  在使用高温计测量炉管表面温度时,反射辐射对测量的影响颇为严重,必须加以修正.几何因子是作这种反射修正的关键数据.本文提出一种计算几何因子的方法,同时计算了Topsφe转化炉和Lummus裂解炉的几何因子,并与某公司的推荐数值和实验数据作了比较.结果表明计算值与推荐值相当一致,光学高温计的测得值用作者推荐的几何因子作反射修正后与铠装热电偶测得值很接近.  In view of the influences of such factors as the distribution of furnace gas temperature, blackness and furnace wall temperature etc, to develop theoretically a mathematical model completely including above factors to describe the heattransfer from furnace gas into heated objects by radiation in a kind of heating equipments is too complicated even impossible. On the other hand , simulation technique , by which a lot of complicated problem in engineering can be solved practically though still unsolved theoretically,... In view of the influences of such factors as the distribution of furnace gas temperature, blackness and furnace wall temperature etc, to develop theoretically a mathematical model completely including above factors to describe the heattransfer from furnace gas into heated objects by radiation in a kind of heating equipments is too complicated even impossible. On the other hand , simulation technique , by which a lot of complicated problem in engineering can be solved practically though still unsolved theoretically, has already been in common use in many fields of engineering design. Thus, an attempt has been made to formulate heattransfer in different kinds of fireheating equipments in steel industry with simulation technique so as to realize the computerized thermal calculation.Summary. A concept "simulation parameter" is put forward taking a dimensionless form in which all the theoretically unsolvable terms are included. Using the values measured in a certain extent, simulation parameters or coefficients would be able to be determined by trial and error. Proceeding from experimental data and based on the theory of heattransfer by radiation , the total heat exchange factor φCG, for example , is regarded as a simulation parameter for slab reheating furnace. Values of φCG have been assigned to be 0.64 and 0.3 for heavy oil and gas firings respectively. In the mean time, furnace gas temperature is indicated by a thermocouple being inserted in the combustion chamber across the furnace wall (cf. Fig. 1,2 and 3). A heattransfer model of heated slab is then given aswhere Q is heattransfer power in kcal/m2 φ/ hr, Tg the representative gas temperature(K) and Ts the surface temperature of slab (K). The value of φCG would be more proper if modifying it by a empirical flame blackness obtained from observing flame brightness, thus making the raised temperature of slabs masured in better accordance with that calculated. The thermal calcuation for simulative design of other kinds of heating equipments and thermal processes have been exemplified as well, e. g. φCG determination in a combustion chamber of steam boiler; thermal analysis of a ladel or tundish in continuous casting; thermal calculations of coke oven and rotary kiln; simulation parameter of radiationheated corrugated sheet pack; heattransfer simulation of acetylene heating for preseured welding of reinforced barsjheattransfer simulation of solidification during steel casting taking account of heat convection and solidifying deposition; and methods of determining heat transfer coefficient by use of simulation technique and their application etc.Fig.1 Schematic of 5zone pushertype slab reheating furnaceFig. 2 Simplification of heattransfer calculation of radiation in a furnace Fig. 3 Relationship between blackness εf and toal heatexchange factor φCG in slab rehating furnaceFig.4 Change of φCG along the height of a boiler s combustion chamber Fig.5 Schematic of a combustion chamber with crosssectional spiralwaterpipesFig.6 A ladle preheated by gas burner Fig.7 A CC tundish preheated by gas burnerFig.8 Schematic of coke oven and heattransfer calculation network Fig.9 Specific heattemperature curve Fig.10 Thermal conductivitytemperature curve(coal and cokedeterminedby heattransfer simulation)Fig.11 Pellet heating in rotary kiln and its characterisic numbers φCG and εg for heattransfer simulation ( Tg and Ts are measured by short stopping)Fig.12 Sizes of rotary kiln and pellet for heattransfer mathematical model Fig.13 Radiationheating of corrugated sheet packFig.14 Absorbing and reflecting of radiations in corrugated sheet pack Fig.15 Simplified heattransfer model of corrugated sheet pack Fig.16 Heating of pressured welding of RC bars Fig.17 Heattransfer model of acetylene heated RC bars Fig.18 Heattransfer simulation parameterapparent distribution of latentheat in solidification during steel casting Fig.19 Heattransfer simulation for shaft watercoolingFig.20 Heattransfer simulation for melting loss  at, blast furnace tuyere due to hotir  把工程设计中广泛应用的模拟技术引入燃烧传热设备中。提出模拟参数的概念,使得用计算机模拟研究热工设备合理结构参数和最佳操作条件的方法简易而实用。以此为基础,针对不同热工设备灵活选择模拟参数,并辅以实验确定之,建立相应的传热数学模型。就板坯加热炉等若干钢铁行业的重要设备说明了这种传热模型的建立和过程模拟方法。   << 更多相关文摘 
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