Zhou Jie-min

Kinetic model on coke oven gas with steam reforming

The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3 and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio of H2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%.

Determination of thermal conductivity of magnesium-alloys

An indirect method, Angstroms method was adopted and an instrument was designed to determine the thermal conductivity of magnesium metal and alloys. Angstroms method is an axial periodic heat flow technique by which the thermal diffusivity can be measured directly. Then thermal conductivity can be obtained with relation to thermal diffusivity. Compared with the recommended data from the literature the fitted values of the thermal diffiusivity correspond with 3%, and the credible probability of the thermal conductivity in the range of 0–450 °C is about 95%. The method is applicable in the given temperature range.

Numerical simulation of thermal process and energy saving of lime furnace

Based on the principle of thermal balance and material balance of lime furnace, the reaction and heat transfer process mathematical-physical model and the on-line monitoring model of the decomposition rate of limestone were set up. With this model, numerical simulation is used to analyze the effects of operational parameters on the process of lime calcining and to optimize it. By using visual basic program to communicate and program, the centralized management and automatic control of the lime furnace are realized. The software is put into practical production, which makes the lime furnace operate steadily and efficiently, and causes the increase in output and decrease in energy consumption.

Study on Compulsive Cooling of Straight Impinging Jet Array and Swirling Jet Impingement

Impinging jet is one of the ideal schemes to satisfy the heat dissipation requirement of the high power chips. In this research, experiments are carried out to investigate the heat transfer between the straight impinging jet array and an iso-heat-flux simulant chip (a heated epoxy resin plate). In the heat transfer experiments, two kinds of jet array are considered, the circular array and the four square array. In some range of flux of the air jet and nozzle-to-plate spacing, the influence of the different arrangement of the spout on average heat transfer of the target plate is discussed. Furthermore, the heat transfer effect of the jet array is compared to the single orifice nozzle which has the same flow area with the array nozzle. Meanwhile, numerical simulation is performed to study the heat transfer effect of the swirling impinging jet in this paper. The angular velocity of the swirling jet, the flow Reynolds number, the dimension of the nozzle and the nozzle-to-plate spacings are examined, then the distribution of both local and average heat transfer coefficient (Nusselt number) on the simulant chip is obtained.

Simulation of the influence of the baffle on flowing field in the anode baking ring furnace

In an anode baking horizontal flue ring furnace, the temperature distribution is one of the key factors influencing the quality of baked anode and is closely correlated with the gas flow. To understand the gas flow distribution in the flue, Navier-Stokes equation with “κ-ε” two-equation turbulence model was adopted and the simulation on the gas flow was performed. The numerical simulation results showed that the even direction of gas flow should be considered in the design of flue baffles and the gas flow distribution was really uneven in the flue in practical use. By adjusting the number and location of flue baffles rationally, the even distribution of gas flow can be improved obviously.

Heat transfer in high density electronics packaging

In order to get an insight into the thermal characteristic and to evaluate the thermal reliability of the “System in Packaging” (SIP), a new solution of electronics packaging, a heat transfer model of SIP was developed to predict the heat dissipation capacity and to investigate the effect of different factors on the temperature distribution in the electronics. The affecting parameters under consideration include the thermophysical properties of the substrates, the coefficient of convection heat transfer, the thickness of the chip, and the density of power dissipation. ALGOR, a kind of finite element analysis software, was used to do the model simulation. Based on the simulation and analysis of the heat conduction and convection resistance, criteria for the thermal design were established and possible measurement for enhancing power dissipation was provided. The results show that the heat transfer model provides a new and effective way to the thermal design and thermal analysis of SIP and to the mechanical analysis for the further investigation of SIP.

Electrolyte temperature based control method for aluminum fluoride addition in Hall-Héroult cell

Addition of aluminum fluoride is an important parameter adopted to control electrolyte temperatures in Hall-Heroult cells. However, determination of the optimal addition is still a difficult issue. This paper puts forward a new control method to select the present-day aluminum fluoride addition optimally based on the yesterday electrolyte temperature. Experiments were carried out on two industrial cells with the same cell age. A proposed prediction correlation for the aluminum fluoride addition was derived from the regression analysis of the test data. The results show that the cell performance is fairly stable through adopting the predicted aluminum fluoride addition in comparison with the existing control method. In view of its simplicity and practicability, this prediction method for aluminum fluoride addition is acceptable in the industrial field.

Experimental Research on Heat Transfer of Confined Air Jet Impingement with Tiny Size Round Nozzle in High Density Electronics Packaging Model

As the heat generation density of electronics packaging grow fast during recent years, the problem of heat dissipation of electronics become the obstruction of development of electronic packaging industry, which accelerated the research and development of heat transfer on the direction of microcosmic. In this research, an epoxy resin laminate heated by heating element was used as the heat transfer surface of simulated chip, and the thermocouples were mounted symmetrically along the diagonal of the laminate to measure the temperature distribution of the surface. Air jet, driven by a small pump, comes from round nozzles (1.5mm and 1mm in diameter) and impinges on the heat transfer surface with middle and low Reynolds number. The parameters such as Reynolds number and height-to-diameter ratio was changed to investigate the radial distribution of Nusselt number and the characteristics of heat transfer in stagnant section. This experimental research gives useful information for the application of air jet impingement to the cooling of electronics packaging

An intelligent decision support system (IDSS) on the process of nickel matte smelter

This paper describes the structure and function of the intelligent decision support system (IDSS) on the process of nickel matte smelter. The knowledge and model base system based on fuzzy-decision rules are specially suggested. The IDSS possesses the self-learning and adaptive properties, and has been used for managing and analyzing the production information, optimizing the composition of the charge mixture, and deciding the optimal operational conditions. Electric energy consumption has been reduced remarkably and the yield of nickel has been increased.This paper describes the structure and function of the intelligent decision support system (IDSS) on the process of nickel matte smelter. The knowledge and model base system based on fuzzy-decision rules are specially suggested. The IDSS possesses the self-learning and adaptive properties, and has been used for managing and analyzing the production information, optimizing the composition of the charge mixture, and deciding the optimal operational conditions. Electric energy consumption has been reduced remarkably and the yield of nickel has been increased.

Determination of Thermal Conductivity of Inorganic Salts at the Liquid/Solid Phase Transition Point

Based on the relationship between the speed of the moving interface and the thermophysical properties of two phases during melting and solidification processes, a measuring apparatus was designed to determine the thermal conductivity of inorganic salts. Using sodium nitrate as the sample, an experiment was carried out to determine its thermal conductivity at the melting point. However, it was difficult to realize the one-dimensional conduction in phase change chamber, which caused the inaccuracy of the data of thermophysical properties from the analytical solutions. So the combination of experiment test and numerical simulation was applied. Compared the experimental result and corrective result of thermal conductivity of sodium nitrate with the value recommended in reference errors are less than 9%and 2%.